[connectors] Google Sheets connector (read + write) — the hotels-list case

[serge-ivo]

[connectors] Google Sheets connector (read + WRITE) — the "populate my hotels list" case

The concrete write example: an agent finds hotels and appends them to the user's Google Sheet for booking.

Do

• Google connector extended with Sheets scope (spreadsheets), reusing the existing Google OAuth (lib/connector-oauth.ts / Drive). grantModel: instance-resource = a specific spreadsheet.
• Tools: sheets_list (granted spreadsheets), sheets_read_range, sheets_append_rows, sheets_update_range.
• Also generalize Drive to expose live read tools (drive_list, drive_read_file) rather than ingest-only — proves the framework beyond one integration.
• WRITE is new to the platform (all connectors are read-only today): needs the connector's write scope + subscriber consent + an approval gate for writes (see the safety issue).

Acceptance

• Connect Google + grant a spreadsheet → an agent can read it and sheets_append_rows new rows (the hotels flow), gated by consent.
• Read-only grant can't write; ungranted spreadsheet rejected.
• Drive live-read tools work via the same framework.

Depends on the connector framework + safety issue (for write consent). Part of the epic.