fix(crm): return valid record update responses

[rudycelekli]

What changed

• Return a real HTTP 404 when a CRM update targets a missing record. Returning a (dict, 404) tuple failed FastAPI's response_model=dict validation and produced HTTP 500.
• Serialize persisted column values for successful updates. Returning the ORM object's raw __dict__ included SQLAlchemy InstanceState, so ordinary updates committed but then returned HTTP 500.

Verified

Ran the public PATCH /api/data/{id} route through FastAPI with a real SQLite database and an operator fixture. No CRM/provider requests were mocked or sent by these new route regressions.

Upstream main	This branch
Missing record: HTTP 500.	HTTP 404 with Record with id 999 not found; existing records unchanged.
Existing record: changes commit, then response serialization fails with HTTP 500.	HTTP 200 with the persisted notes, used flag and unchanged name; a fresh database read confirms the update.

• Focused CRM route/import suite: 20 passed.
• Frozen backend selection: 1,880 passed, 131 skipped, 3 deselected, 3 deprecation warnings. No production or user database was used.
• PostgreSQL service tests were not run locally; hosted checks remain pending. No frontend source changed, and no frontend build is claimed.
• Screened current open PR files for overlap; no other open PR changes this handler or these new regression tests. Authentication and workspace behavior are unchanged.

AI assistance: implemented and tested with Codex on behalf of Rudy Celekli. The exact signed DCO patch received a separate source review before publication.