feat(phase-33): add 4 graph analytics endpoints to api/routes/graph.py

fix(BUG-1): use str(depth_safe) literal in Cypher path pattern -- Neo4j rejects parameters in *min..max

fix(api+graph+pipeline): M-04+M-05+M-08+M-09 -- misc medium fixes

fix(api+ai): M-01+M-02+M-03 -- version consistency and duplicate assignments

fix(encoding): strip non-ASCII chars from all modified files

fix(api): BUG-10 -- deduplicate graph edges before sending to frontend

fix(api): BUG-10 -- deduplicate graph edges before sending to frontend

fix(BUG-09): depth via Cypher param not f-string; use explicit node/rel RETURN

fix(search+graph+frontend): 6 issues resolved

feat(api): FastAPI backend with entity search, dossier, graph, and risk endpoints