feat: 3 new tools, format streaming, distribution-ready demo + landing pages

Tools shipped this batch (4 → 6 of 9 Ready):
  04 Missing Value Handler   src/core/missing.py + cli_missing.py + GUI
  05 Column Mapper           src/core/column_mapper.py + cli_column_map.py + GUI
  09 Pipeline Runner         src/core/pipeline.py + cli_pipeline.py + GUI
                             with soft tool-dependency graph (recommended,
                             not enforced) and JSON save/load for repeatable
                             weekly cleanups.

Format Standardizer reworked for 1 GB international files:
  • Vectorised dispatch + LRU cache over phone/date/currency/boolean/email
  • Per-row country / address columns drive parsing
  • Audit cap (default 10 k rows, ~50 MB RAM)
  • standardize_file(): chunked streaming entry point (~165 k rows/sec)
  • currency_decimal="auto" for EU comma-decimal locales
  • R$ / kr / zł multi-char currency prefixes
  • cli_format.py with auto-stream above 100 MB inputs

Encoding detection arbiter + language-aware probe:
  Closes the last 4 xfails (cp1250 / mac_iceland / shift_jis_2004 / lying-BOM)
  via tied-confidence arbiter + Cyrillic / EE-Latin coverage probes.

Distribution-readiness assets:
  • streamlit_app.py — Streamlit Community Cloud entry shim
  • src/gui/app_demo.py — single-page demo, ?p=<persona> routing,
    100-row cap + watermark, free-vs-paid boundary enforced at surface
  • samples/demo/ — 3 niche datasets + pre-tuned pipeline JSONs
  • landing/ — 4 static HTML pages (apex chooser + 3 niche),
    shared CSS, deploy.py URL-substitution script,
    auto-generated robots.txt + sitemap.xml + 404.html + favicon
  • docs/PLAN.md, DEMO-PLAN.md, DEPLOYMENT.md, POST-LAUNCH.md, NEXT-STEPS.md
    — full strategy + measurement + deployment + master checklist

Test counts:
  before: 1,520 passed · 4 skipped · 17 xfailed
  after:  1,729 passed · 0 skipped · 0  xfailed

Tier-1 corpora added:
  • missing-corpus           3 use cases + 16 edge cases
  • column-mapper-corpus     3 use cases + 5 edge cases
  • format-cleaner intl      20-row 13-country stress fixture

Engine hardening flushed out by the corpora:
  • interpolate guards against object-dtype columns
  • mean/median skip all-NaN columns (silences numpy warning)
  • fillna runs under future.no_silent_downcasting (silences pandas warning)
  • mojibake test no longer skips when ftfy installed (monkeypatch path)
  • drop-row threshold semantics: strict-greater (consistent across rows / cols)
  • currency_decimal validator allow-set updated for "auto"

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

landing/_shared/styles.css

@@ -0,0 +1,234 @@
+/* DataTools landing-page styles — single shared sheet for all niches.
+ *
+ * Design constraints:
+ *   • No external font / CSS dependencies (works on Cloudflare Pages
+ *     with zero build step, no privacy banner needed).
+ *   • Mobile-first; layout reflows below 720 px.
+ *   • Dark, focused, content-first. Buyer reads this on a laptop
+ *     between Shopify exports — keep it readable and skimmable.
+ *   • Persona pages all share this sheet — niche differences live in
+ *     copy + accent-color variables overridden in each page's <style>.
+ */
+
+:root {
+  --bg:           #0f1115;
+  --surface:      #161922;
+  --surface-2:    #1d212b;
+  --text:         #e8eaed;
+  --text-mute:    #9aa3b2;
+  --text-soft:    #c8ced8;
+  --rule:         #252a36;
+  --accent:       #6ee7b7;          /* Shopify pet default — overridden per persona */
+  --accent-ink:   #052e1a;
+  --warn:         #fbbf24;
+  --max:          1080px;
+  --radius:       12px;
+  --shadow:       0 1px 3px rgba(0,0,0,0.3), 0 8px 24px rgba(0,0,0,0.2);
+  --mono:         ui-monospace, SFMono-Regular, "SF Mono", Menlo, monospace;
+  --sans:         -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
+                  "Helvetica Neue", Arial, sans-serif;
+}
+
+* { box-sizing: border-box; }
+
+html, body {
+  margin: 0; padding: 0;
+  background: var(--bg);
+  color: var(--text);
+  font-family: var(--sans);
+  font-size: 16px;
+  line-height: 1.55;
+  -webkit-font-smoothing: antialiased;
+}
+
+a { color: var(--accent); text-decoration: none; }
+a:hover { text-decoration: underline; }
+
+/* ----- Sticky buy bar ----- */
+.buybar {
+  position: sticky; top: 0; z-index: 50;
+  background: rgba(15,17,21,0.92);
+  backdrop-filter: blur(8px);
+  border-bottom: 1px solid var(--rule);
+  padding: 10px 20px;
+}
+.buybar-inner {
+  max-width: var(--max); margin: 0 auto;
+  display: flex; align-items: center; justify-content: space-between;
+  gap: 16px;
+}
+.buybar .brand { font-weight: 600; letter-spacing: -0.01em; }
+.buybar .brand-mark { color: var(--accent); margin-right: 6px; }
+.buybar .price-tag { color: var(--text-mute); font-size: 14px; margin-right: 12px; }
+
+/* ----- Buttons ----- */
+.btn {
+  display: inline-block;
+  background: var(--accent); color: var(--accent-ink);
+  font-weight: 600; font-size: 15px;
+  padding: 11px 18px; border-radius: 8px;
+  border: 0; cursor: pointer;
+  transition: transform 0.05s ease, box-shadow 0.15s ease;
+}
+.btn:hover { transform: translateY(-1px); text-decoration: none; box-shadow: var(--shadow); }
+.btn-large {
+  padding: 14px 24px; font-size: 17px;
+}
+.btn-ghost {
+  background: transparent; color: var(--text-soft);
+  border: 1px solid var(--rule);
+}
+.btn-ghost:hover { background: var(--surface); }
+
+/* ----- Layout ----- */
+section {
+  padding: 60px 20px;
+  border-bottom: 1px solid var(--rule);
+}
+section:last-of-type { border-bottom: 0; }
+.container { max-width: var(--max); margin: 0 auto; }
+
+h1, h2, h3 { line-height: 1.2; letter-spacing: -0.02em; margin-top: 0; }
+h1 { font-size: 44px; margin-bottom: 18px; }
+h2 { font-size: 30px; margin-bottom: 16px; }
+h3 { font-size: 19px; margin-bottom: 8px; }
+p  { margin: 0 0 14px 0; color: var(--text-soft); }
+.muted { color: var(--text-mute); }
+.eyebrow { color: var(--accent); font-size: 13px; font-weight: 600;
+           text-transform: uppercase; letter-spacing: 0.08em; margin-bottom: 10px; }
+
+ul.bullets { padding-left: 20px; margin: 0 0 14px 0; }
+ul.bullets li { margin-bottom: 8px; color: var(--text-soft); }
+
+/* ----- Hero ----- */
+.hero {
+  padding: 80px 20px 60px;
+  background: radial-gradient(ellipse at top, var(--surface), var(--bg) 60%);
+}
+.hero h1 strong { color: var(--accent); font-weight: 700; }
+.hero .lead {
+  font-size: 19px; color: var(--text-soft); max-width: 720px;
+  margin-bottom: 28px;
+}
+.hero .cta-row { display: flex; gap: 12px; flex-wrap: wrap; align-items: center; }
+.hero .price-note { color: var(--text-mute); font-size: 14px; }
+
+/* ----- Demo embed ----- */
+.demo-frame {
+  background: var(--surface);
+  border: 1px solid var(--rule);
+  border-radius: var(--radius);
+  overflow: hidden;
+  box-shadow: var(--shadow);
+}
+.demo-frame iframe {
+  width: 100%; height: 720px; border: 0; display: block;
+  background: var(--surface-2);
+}
+.demo-caption {
+  font-size: 14px; color: var(--text-mute);
+  padding: 10px 16px; border-top: 1px solid var(--rule);
+}
+
+/* ----- Cards / grids ----- */
+.grid {
+  display: grid; gap: 18px;
+  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
+}
+.card {
+  background: var(--surface);
+  border: 1px solid var(--rule);
+  border-radius: var(--radius);
+  padding: 22px;
+}
+.card h3 { color: var(--text); }
+.card p:last-child { margin-bottom: 0; }
+.card .icon {
+  display: inline-block; font-size: 22px; margin-bottom: 8px;
+}
+
+/* ----- Stats row ----- */
+.stats { display: flex; gap: 28px; flex-wrap: wrap; margin: 18px 0 0; }
+.stats .stat .num {
+  font-family: var(--mono); font-size: 26px; font-weight: 600;
+  color: var(--accent);
+}
+.stats .stat .label { font-size: 13px; color: var(--text-mute); }
+
+/* ----- Privacy / audit callout panels ----- */
+.callout {
+  background: var(--surface);
+  border-left: 3px solid var(--accent);
+  border-radius: 0 var(--radius) var(--radius) 0;
+  padding: 18px 22px;
+  margin: 18px 0;
+}
+.callout strong { color: var(--text); }
+
+/* ----- Code-ish blocks ----- */
+.terminal {
+  font-family: var(--mono); font-size: 14px;
+  background: #0a0c10;
+  color: #d8dfe8;
+  border: 1px solid var(--rule);
+  border-radius: var(--radius);
+  padding: 16px 18px;
+  overflow-x: auto;
+  white-space: pre;
+  line-height: 1.45;
+}
+.terminal .prompt { color: var(--text-mute); }
+.terminal .ok { color: var(--accent); }
+.terminal .warn { color: var(--warn); }
+
+/* ----- Pricing ----- */
+.pricing {
+  display: grid; gap: 18px;
+  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
+}
+.pricing .card .price {
+  font-size: 38px; font-weight: 700; letter-spacing: -0.02em;
+  color: var(--text);
+}
+.pricing .card .price-suffix { font-size: 14px; color: var(--text-mute); margin-left: 4px; }
+.pricing .card.featured { border-color: var(--accent); }
+.pricing .card .row { display: flex; align-items: baseline; gap: 4px; margin-bottom: 12px; }
+.pricing .card ul { padding-left: 18px; margin: 12px 0 18px; }
+.pricing .card li { color: var(--text-soft); margin-bottom: 6px; }
+
+/* ----- FAQ ----- */
+details.faq {
+  border-bottom: 1px solid var(--rule);
+  padding: 14px 0;
+}
+details.faq summary {
+  font-weight: 600; color: var(--text);
+  cursor: pointer; list-style: none;
+  display: flex; align-items: center; justify-content: space-between;
+}
+details.faq summary::after {
+  content: "+"; color: var(--accent); font-size: 22px;
+  margin-left: 14px;
+}
+details.faq[open] summary::after { content: "−"; }
+details.faq p { margin-top: 10px; }
+
+/* ----- Footer ----- */
+footer {
+  padding: 40px 20px 60px;
+  font-size: 14px;
+  color: var(--text-mute);
+}
+footer .container { display: flex; gap: 28px; flex-wrap: wrap; justify-content: space-between; }
+footer a { color: var(--text-soft); }
+footer p { color: var(--text-mute); }
+
+/* ----- Responsive ----- */
+@media (max-width: 720px) {
+  h1 { font-size: 32px; }
+  h2 { font-size: 24px; }
+  section { padding: 40px 18px; }
+  .hero { padding: 56px 18px 40px; }
+  .demo-frame iframe { height: 560px; }
+  .buybar-inner .price-tag { display: none; }
+}