docs(sync): document google revocation and reconnect behavior

[cursor]

Updates sync/runtime/API docs to reflect current Google revocation handling, reconnect lifecycle, metadata shape (google.hasRefreshToken), and notification/import response semantics. Also documents res.promise 204 status-only responses used by event write endpoints.

  

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Note

Low Risk
Docs-only changes; no runtime behavior or contracts are modified, but inaccuracies could mislead implementers if not reviewed for correctness.

Overview
Documentation updates clarify Google revocation/reconnect behavior end-to-end across API, websocket, and frontend runtime, including how clients should react to GOOGLE_REVOKED (keep session, fall back to local storage, prompt reconnect) and how reconnect restarts sync.

Docs now spell out the UserMetadata shape (including google.hasRefreshToken enrichment), expected outcomes/status codes for Google notification handling and /api/sync/import-gcal, and the backend convention of returning { statusCode: 204 } via res.promise(...) for true 204 No Content responses on event write endpoints.

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