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/components/dedup_review.py

@@ -0,0 +1,24 @@
+"""Dedup match-group cards and review pipeline.
+
+The interactive dedup-review surface — config panel, match-group cards,
+results summary, and apply-decisions glue. This is the largest single
+chunk of the GUI by line count; isolating it in a seam module means a
+non-dedup SKU never has to import it (and never has to drag in
+``src.core.dedup`` along the way).
+"""
+
+from __future__ import annotations
+
+from ._legacy import (
+    apply_review_decisions,
+    config_panel,
+    match_group_card,
+    results_summary,
+)
+
+__all__ = [
+    "apply_review_decisions",
+    "config_panel",
+    "match_group_card",
+    "results_summary",
+]