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)

code_review_graph/main.py

@@ -28,6 +28,7 @@ from .prompts import (
     onboard_developer_prompt,
     pre_merge_check_prompt,
     review_changes_prompt,
+    unified_review_prompt,
 )
 from .tools import (
     apply_refactor_func,
@@ -1124,6 +1125,21 @@ def pre_merge_check(base: str = "HEAD~1") -> list[dict]:
     return pre_merge_check_prompt(base=base)
 
 
+@mcp.prompt()
+def unified_review(base: str = "HEAD~1", tier: str = "standard") -> list[dict]:
+    """Three-layer unified review (CRG graph context + scoring + dedupe + report).
+
+    Fuses graph context with the objective scoring metrics, finding merge,
+    and the standalone HTML report.  READ-ONLY: every finding waits for a
+    manual fix decision.
+
+    Args:
+        base: Git ref to diff against. Default: HEAD~1.
+        tier: Review tier (fast / standard / strict). Default: standard.
+    """
+    return unified_review_prompt(base=base, tier=tier)
+
+
 def _apply_tool_filter(tools: str | None = None) -> None:
     """Remove tools not listed in the allow-list.