docs: add graphify knowledge graph integration

Ignore graphify-out/ (local graph data) and document query/update
workflow in CLAUDE.md for future codebase questions.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitignore

@@ -4,3 +4,4 @@
 *.db-wal
 backend/server
 .playwright-mcp/
+graphify-out/

CLAUDE.md

@@ -58,3 +58,13 @@ Smoke test: `curl` the endpoints with `Authorization: Bearer <token>`; confirm `
 ## Relevant skills
 
 `multi-stage-dockerfile` and `docker-compose-orchestration` for the container work (referenced in the plan).
+
+## graphify
+
+This project has a knowledge graph at graphify-out/ with god nodes, community structure, and cross-file relationships.
+
+Rules:
+- For codebase questions, first run `graphify query "<question>"` when graphify-out/graph.json exists. Use `graphify path "<A>" "<B>"` for relationships and `graphify explain "<concept>"` for focused concepts. These return a scoped subgraph, usually much smaller than GRAPH_REPORT.md or raw grep output.
+- If graphify-out/wiki/index.md exists, use it for broad navigation instead of raw source browsing.
+- Read graphify-out/GRAPH_REPORT.md only for broad architecture review or when query/path/explain do not surface enough context.
+- After modifying code, run `graphify update .` to keep the graph current (AST-only, no API cost).