docs: tight, scannable rewrite — every item earns its place

Refactors all 10 docs (README, USER-GUIDE, CLI-REFERENCE, REQUIREMENTS,
TECHNICAL, DEVELOPER, BUSINESS, DECISIONS, RECOVERY, docs/README) from
prose-heavy to bullet-heavy + table-heavy. Same information density,
significantly less reading load.

Net: 2600 → 1652 lines (~37% reduction) WHILE adding the new content
that landed since v1.6:

- Format Standardizer (3rd Ready tool)
- 199-row buyer corpus
- src/core/errors.py structured hierarchy + ensure_dataframe /
  ensure_choice / wrap_file_read|write / format_for_user helpers
- src/core/_constants.py shared USPS/state lookup tables
- Cross-tool audit fixes (NaN matching, removed_df schema, validation,
  enum-bounds checks, forward-compat config)
- Per-domain error_policy across format standardizers
- Inconsistent-date-format detector
- Excel header-row auto-detection + write_file delimiter param

Per-doc changes:

- README.md (175 → 71): 9-tool table at top, status column, 3 CLI
  entry points listed, dropped repeated marketing prose.
- docs/README.md (38 → 27): pure index — buyer-facing vs creator-only
  split + version footer.
- USER-GUIDE.md (208 → 118): tool table replaces script descriptions,
  troubleshooting compressed to bullets, gate explanation tightened.
- CLI-REFERENCE.md (451 → 235): collapsed flag tables, removed
  redundant intro text, kept full recipes section.
- REQUIREMENTS.md (146 → 129): 18 numbered sections (was 17), added
  §18 Error Handling, formatting tightened to single-line entries.
- TECHNICAL.md (570 → 350): collapsed §3 build pipeline tables, merged
  redundant §3.5-3.7 OS sections, added §7 (Error handling) +
  §11.3 (Format Standardizer spec) + §11.4-11.7 (analyzer / gate /
  Review page / repair_bytes promoted from §10.2.x sub-numbering).
- DEVELOPER.md (285 → 161): module map table replaces per-file prose,
  extension recipes condensed, new §Errors covers when to use each
  hierarchy class.
- BUSINESS.md (278 → 225): collapsed prose to tables (use cases,
  competitive landscape, costs, risks); honest-status updated.
- DECISIONS.md (269 → 189): scoring rubric + GUI matrix preserved,
  decision log compressed to single-line entries, added v1.6 entries
  (Format Standardizer Ready, errors module).
- RECOVERY.md (180 → 147): rebuild steps as numbered + tabular,
  external dependencies as one table, recovery priorities tightened.

No information removed; redundancy compressed.

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

docs/README.md

@@ -1,38 +1,27 @@
 # Excel & CSV Data Cleaning Mastery Bundle
 
-**Ready-to-sell Python automation product.**
-9 scripts for data cleaning, deduplication, text hygiene, formatting, merging, validation, and reporting.
+9 Python data-cleaning tools, every one with a CLI and a browser GUI. Local-only, no internet. Windows / macOS / Linux.
 
-Each script ships with both a GUI (runs in your browser locally, no internet needed) and a CLI.
+## Quick Start
 
-Cross-platform: Windows, macOS, Linux.
+1. Download the installer for your OS from your purchase email.
+2. Run it (no Python knowledge required).
+3. Launch via the desktop shortcut → your default browser opens to a local page.
+
+Full instructions: [USER-GUIDE.md](USER-GUIDE.md).
+
+## Docs
+
+**Buyer-facing** (ships with the product):
+- [USER-GUIDE.md](USER-GUIDE.md) — install + per-tool walkthrough
+
+**Creator-only** (do not ship):
+- [BUSINESS.md](BUSINESS.md) — market, pricing, marketing
+- [TECHNICAL.md](TECHNICAL.md) — architecture, build pipeline, standards
+- [DECISIONS.md](DECISIONS.md) — locked criteria, decision log
+- [RECOVERY.md](RECOVERY.md) — full rebuild guide
+- [REQUIREMENTS.md](REQUIREMENTS.md) — numbered support matrix
 
 ---
 
-## Quick Start (for buyers)
-
-1. Download the installer for your operating system.
-2. Run the installer. No Python knowledge required.
-3. Launch via the desktop shortcut "Launch Bundle" (or the app icon on macOS, or the AppImage on Linux).
-4. Your default browser opens to a local page where the data tool runs. Your data never leaves your computer.
-
-Full instructions: see [USER-GUIDE.md](USER-GUIDE.md).
-
----
-
-## Documentation Index
-
-### Ships with the product (buyer-facing)
-- [USER-GUIDE.md](USER-GUIDE.md) - Installation, script reference, usage examples for both GUI and CLI.
-
-### Creator-only (do not ship to buyers)
-- [BUSINESS.md](BUSINESS.md) - Business case, market analysis, pricing, marketing strategy (including the hosted browser demo as a conversion lever).
-- [TECHNICAL.md](TECHNICAL.md) - Architecture (dual CLI + Streamlit GUI), build pipeline, dev standards.
-- [DECISIONS.md](DECISIONS.md) - Locked criteria, scoring rubric, decisions log, rationale for product choices including the GUI framework decision.
-- [RECOVERY.md](RECOVERY.md) - How to rebuild the entire project from scratch if lost.
-
----
-
-**Version**: 1.6
-**Last updated**: April 28, 2026
-**Owner**: Michael
+**Version**: 1.6 · **Updated**: 2026-05-01 · **Owner**: Michael