refactor(gui): tool registry + components package for per-tool builds

Two low-risk seam moves to enable selling per-tool subsets without
breaking the existing all-in-one bundle. Behaviour identical; every
existing import still resolves; full pytest suite + every page returns
HTTP 200.

1. **Tool registry** (src/gui/tools_registry.py) — replaces the
   inline dict-of-dicts in app.py with a Tool dataclass and a TOOLS
   list. Adds a tier field ("core" today, "pro" / "enterprise" later)
   and tools_for_tier() / tool_by_id() / display_name() helpers. A
   per-tool build slices TOOLS at import time without code changes.

2. **components package** (src/gui/components/) — converts the former
   single components.py into a package with:
     _legacy.py        — original file, unchanged.
     __init__.py       — re-exports the legacy surface; existing
                         "from src.gui.components import …" calls
                         continue to work.
     shared.py         — hide_streamlit_chrome, pickup_or_upload
                         (every build needs these).
     gate.py           — require_normalization_gate (Pro / Suite SKUs).
     findings.py       — analyzer-finding widgets (drops out of a
                         standalone-Dedup build).
     dedup_review.py   — match-group cards + apply pipeline (drops out
                         of a non-dedup build).

   The seam modules are narrow re-exports today. As code migrates out
   of _legacy.py into the focused modules, the public import path
   stays stable via the shim.

E2E: 765 passed, 17 xfailed (unchanged); home page + all 9 tool pages
+ Review page render HTTP 200; full pipeline (analyze → auto_fix →
apply_decisions → output bytes) round-trips on the kitchen-sink
fixture with zero high-confidence findings remaining post-fix.

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

src/gui/app.py

@@ -57,80 +57,7 @@ st.divider()
 # Tool cards
 # ---------------------------------------------------------------------------
 
-TOOLS = [
-    {
-        "icon": "🔍",
-        "name": "Deduplicator",
-        "description": "Fuzzy matching, normalization, survivor selection, and interactive review.",
-        "status": "Ready",
-        "page": "1_Deduplicator",
-        "tool_id": "01_deduplicator",
-    },
-    {
-        "icon": "✂️",
-        "name": "Text Cleaner",
-        "description": "Whitespace trim, multi-space collapse, Unicode normalization, BOM and line-ending handling.",
-        "status": "Ready",
-        "page": "2_Text_Cleaner",
-        "tool_id": "02_text_cleaner",
-    },
-    {
-        "icon": "📐",
-        "name": "Format Standardizer",
-        "description": "Standardize dates, currencies, names, phone numbers, and addresses.",
-        "status": "Coming Soon",
-        "page": "3_Format_Standardizer",
-        "tool_id": "03_format_standardizer",
-    },
-    {
-        "icon": "🕳️",
-        "name": "Missing Value Handler",
-        "description": "Detect disguised nulls, missingness analysis, and imputation strategies.",
-        "status": "Coming Soon",
-        "page": "4_Missing_Values",
-        "tool_id": "04_missing_handler",
-    },
-    {
-        "icon": "🗂️",
-        "name": "Column Mapper",
-        "description": "Rename columns, enforce a target schema, and coerce types.",
-        "status": "Coming Soon",
-        "page": "5_Column_Mapper",
-        "tool_id": "05_column_mapper",
-    },
-    {
-        "icon": "📊",
-        "name": "Outlier Detector",
-        "description": "Z-score, IQR, and MAD detection with domain-rule violations and winsorization.",
-        "status": "Coming Soon",
-        "page": "6_Outlier_Detector",
-        "tool_id": "06_outlier_detector",
-    },
-    {
-        "icon": "📎",
-        "name": "Multi-File Merger",
-        "description": "Combine multiple CSV/Excel files with schema alignment.",
-        "status": "Coming Soon",
-        "page": "7_Multi_File_Merger",
-        "tool_id": "07_multi_file_merger",
-    },
-    {
-        "icon": "✅",
-        "name": "Validator & Reporter",
-        "description": "Validate against rules and generate PDF/Excel quality reports.",
-        "status": "Coming Soon",
-        "page": "8_Validator_Reporter",
-        "tool_id": "08_validator_reporter",
-    },
-    {
-        "icon": "⚙️",
-        "name": "Pipeline Runner",
-        "description": "Chain tools in recommended order and pass output between steps.",
-        "status": "Coming Soon",
-        "page": "9_Pipeline_Runner",
-        "tool_id": "09_pipeline_runner",
-    },
-]
+from src.gui.tools_registry import TOOLS
 
 # Render tool cards in a 3-column grid. Cards picked up by the analyzer get a
 # coloured "N findings" badge so the user can see at a glance which tools
@@ -143,15 +70,15 @@ for row_start in range(0, len(TOOLS), 3):
             break
         tool = TOOLS[idx]
         with col:
-            status_color = "green" if tool["status"] == "Ready" else "orange"
+            status_color = "green" if tool.status == "Ready" else "orange"
             badge = ""
-            n = findings_count_for_tool(tool.get("tool_id", ""))
+            n = findings_count_for_tool(tool.tool_id)
             if n:
                 badge = f" :red-background[**{n} finding{'s' if n != 1 else ''}**]"
             st.markdown(
-                f"### {tool['icon']} {tool['name']}{badge}\n\n"
-                f"{tool['description']}\n\n"
-                f":{status_color}[**{tool['status']}**]"
+                f"### {tool.icon} {tool.name}{badge}\n\n"
+                f"{tool.description}\n\n"
+                f":{status_color}[**{tool.status}**]"
             )