feat: add unified_review MCP prompt + sync tool/prompt counts

Adds the unified_review MCP prompt (invoked as /code-review-graph:unified_review)
that drives the unified-review workflow: graph context -> detect_changes ->
score_review -> findings -> dedupe_findings -> generate_report. READ-ONLY:
every finding waits for a manual fix decision. Takes base and tier
(fast/standard/strict) arguments.

- prompts.py: unified_review_prompt + docstring count 5->6
- main.py: @mcp.prompt() registration
- tests/test_prompts.py: TestUnifiedReviewPrompt + preamble test
- docs: LLM-OPTIMIZED-REFERENCE, COMMANDS, CLAUDE.md, INDEX, architecture,
  README + 4 localized READMEs; tool count 30->31 and prompt count 5->6
  synced (historical ROADMAP/FEATURES version notes left unchanged)

docs/COMMANDS.md

@@ -310,7 +310,7 @@ kind: str | None
 limit: int = 20
 ```
 
-## MCP Prompts (5 workflow templates)
+## MCP Prompts (6 workflow templates)
 
 ### `review_changes`
 Pre-commit review workflow using detect_changes, affected_flows, and test gaps.
@@ -336,6 +336,16 @@ PR readiness check with risk scoring, test gaps, and dead code detection.
 base: str = "HEAD~1"
 ```
 
+### `unified_review`
+Three-layer unified review: CRG graph context + objective scoring
+(`score_review`), finding merge (`dedupe_findings`), and the standalone
+HTML report (`generate_report`). READ-ONLY: every finding waits for a
+manual fix decision.
+```
+base: str = "HEAD~1"
+tier: str = "standard"   # fast | standard | strict
+```
+
 ## CLI Commands
 
 ```bash