chore: wire up code-review-graph MCP server

- Add .mcp.json registering code-review-graph (uvx, stdio)
- Document the MCP tools in CLAUDE.md so the assistant prefers
  graph queries over Grep/Glob/Read for structural exploration
- Ignore .code-review-graph/ index directory

.gitignore

@@ -53,3 +53,5 @@ Thumbs.db
 # Node.js / esbuild
 node_modules/
 media_server/static/dist/
+# Added by code-review-graph
+.code-review-graph/

.mcp.json

@@ -0,0 +1,12 @@
+{
+  "mcpServers": {
+    "code-review-graph": {
+      "command": "uvx",
+      "args": [
+        "code-review-graph",
+        "serve"
+      ],
+      "type": "stdio"
+    }
+  }
+}

CLAUDE.md

@@ -196,3 +196,42 @@ pytest --tb=short -q
 
 - **ALWAYS ask for user approval before committing and pushing changes.**
 - When pushing, always push to all remotes: `git push origin master && git push github master`
+
+<!-- code-review-graph MCP tools -->
+## MCP Tools: code-review-graph
+
+**IMPORTANT: This project has a knowledge graph. ALWAYS use the
+code-review-graph MCP tools BEFORE using Grep/Glob/Read to explore
+the codebase.** The graph is faster, cheaper (fewer tokens), and gives
+you structural context (callers, dependents, test coverage) that file
+scanning cannot.
+
+### When to use graph tools FIRST
+
+- **Exploring code**: `semantic_search_nodes` or `query_graph` instead of Grep
+- **Understanding impact**: `get_impact_radius` instead of manually tracing imports
+- **Code review**: `detect_changes` + `get_review_context` instead of reading entire files
+- **Finding relationships**: `query_graph` with callers_of/callees_of/imports_of/tests_for
+- **Architecture questions**: `get_architecture_overview` + `list_communities`
+
+Fall back to Grep/Glob/Read **only** when the graph doesn't cover what you need.
+
+### Key Tools
+
+| Tool | Use when |
+|------|----------|
+| `detect_changes` | Reviewing code changes — gives risk-scored analysis |
+| `get_review_context` | Need source snippets for review — token-efficient |
+| `get_impact_radius` | Understanding blast radius of a change |
+| `get_affected_flows` | Finding which execution paths are impacted |
+| `query_graph` | Tracing callers, callees, imports, tests, dependencies |
+| `semantic_search_nodes` | Finding functions/classes by name or keyword |
+| `get_architecture_overview` | Understanding high-level codebase structure |
+| `refactor_tool` | Planning renames, finding dead code |
+
+### Workflow
+
+1. The graph auto-updates on file changes (via hooks).
+2. Use `detect_changes` for code review.
+3. Use `get_affected_flows` to understand impact.
+4. Use `query_graph` pattern="tests_for" to check coverage.