feat: add unified-review workflow (scoring tools + skill)

Adds the unified-review integration that fuses CRG graph context with the
ai-code-review scoring methodology and gstack-review fix-first workflow:

- scoring.py: objective Layer-2 metrics (sql_risk, exception_coverage,
  redundancy_rate, high_risk_density, vulnerability_risk) with
  good/warn/fail grades, plus dedupe_findings (fingerprint merge,
  multi-source confidence boost, PR quality score) and report data builder
- tools/scoring_tools.py + main.py: three new MCP tools
  (score_review_tool, dedupe_findings_tool, generate_report_tool)
- assets/report-template.html: self-contained HTML report template
- skills.py + skills/unified-review/: new read-only unified-review skill
  with language/manual-review/specialist checklists
- docs and CHANGELOG updated; tests added (test_scoring, test_report,
  test_unified_review) and test_skills updated for 5 skills

code_review_graph/tools/__init__.py

@@ -1,6 +1,6 @@
 """MCP tool definitions for the Code Review Graph server.
 
-Exposes 27 tools:
+Exposes 31 tools:
 1. build_or_update_graph  - full or incremental build
 2. get_impact_radius      - blast radius from changed files
 3. query_graph            - predefined graph queries
@@ -29,6 +29,9 @@ Exposes 27 tools:
 26. get_surprising_connections - find unexpected architectural coupling
 27. get_suggested_questions - auto-generated review questions from graph analysis
 28. traverse_graph        - BFS/DFS traversal from best-matching node
+29. score_review          - objective Layer-2 review metrics for changed files
+30. dedupe_findings       - fingerprint dedup + confidence merge for findings
+31. generate_report       - render the standalone HTML code review report
 """
 
 from __future__ import annotations
@@ -103,6 +106,13 @@ from .review import (
     get_review_context,
 )
 
+# -- scoring (unified-review) ------------------------------------------------
+from .scoring_tools import (
+    dedupe_findings_func,
+    generate_report_func,
+    score_review_func,
+)
+
 __all__ = [
     # _common
     "_BUILTIN_CALL_NAMES",
@@ -143,6 +153,10 @@ __all__ = [
     "detect_changes_func",
     "get_affected_flows_func",
     "get_review_context",
+    # scoring (unified-review)
+    "score_review_func",
+    "dedupe_findings_func",
+    "generate_report_func",
     # analysis_tools
     "get_bridge_nodes_func",
     "get_hub_nodes_func",