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)

tests/test_prompts.py

@@ -8,6 +8,7 @@ from code_review_graph.prompts import (
     onboard_developer_prompt,
     pre_merge_check_prompt,
     review_changes_prompt,
+    unified_review_prompt,
 )
 
 
@@ -167,6 +168,52 @@ class TestPreMergeCheckPrompt:
         assert "dead_code" in _text(result[0])
 
 
+class TestUnifiedReviewPrompt:
+    def test_returns_list_with_messages(self):
+        result = unified_review_prompt()
+        assert isinstance(result, list)
+        assert len(result) >= 1
+
+    def test_message_has_role_and_content(self):
+        result = unified_review_prompt()
+        for msg in result:
+            assert isinstance(msg, Message)
+            assert msg.role == "user"
+            assert _text(msg)
+
+    def test_default_base_and_tier(self):
+        result = unified_review_prompt()
+        text = _text(result[0])
+        assert "HEAD~1" in text
+        assert "standard tier" in text
+
+    def test_custom_base_and_tier(self):
+        result = unified_review_prompt(base="develop", tier="strict")
+        text = _text(result[0])
+        assert "base=develop" in text
+        assert "strict tier" in text
+
+    def test_mentions_score_review(self):
+        result = unified_review_prompt()
+        assert "score_review" in _text(result[0])
+
+    def test_mentions_dedupe_findings(self):
+        result = unified_review_prompt()
+        assert "dedupe_findings" in _text(result[0])
+
+    def test_mentions_generate_report(self):
+        result = unified_review_prompt()
+        assert "generate_report" in _text(result[0])
+
+    def test_mentions_read_only(self):
+        result = unified_review_prompt()
+        assert "READ-ONLY" in _text(result[0])
+
+    def test_mentions_blocker_rule(self):
+        result = unified_review_prompt()
+        assert "FAIL" in _text(result[0])
+
+
 class TestTokenEfficiencyPreamble:
     """All prompts should include the token efficiency preamble."""
 
@@ -190,3 +237,7 @@ class TestTokenEfficiencyPreamble:
     def test_pre_merge_has_preamble(self):
         result = pre_merge_check_prompt()
         assert "get_minimal_context" in _text(result[0])
+
+    def test_unified_review_has_preamble(self):
+        result = unified_review_prompt()
+        assert "get_minimal_context" in _text(result[0])