Circuit breaker for Google Workspace comment poller (#1490)

[bingran-you]

Summary

• Google's comments API returns sticky 5xx for some files (staging example: a presentation that permanently returns `500 internalError`). The poller ran `list_comments` every cycle, producing unbounded log spam and wasting Drive API quota.
• Added `CommentCircuitBreaker` keyed on `file_id`. After 5 consecutive failures the file is skipped with exponential cooldown (1m, 2m, 4m ... capped at 30m). Success immediately resets. Warn emitted at trip time, then at most once per hour.
• Wired into all three pollers (Docs, Sheets, Slides) — they share the same failure mode.

Refs #1490

Test plan

• `cargo test -p scheduler_module --lib google_workspace_poller` — 5 new tests pass (threshold, trip, reset, isolation, max cooldown cap)
• `cargo check -p scheduler_module` clean (only pre-existing warnings)
• Verify on staging: gateway no longer emits per-cycle `500 internalError` spam for presentation `1zsQXUFU9sbVLWCojAI0si5Hh_BxS1HvGbwyFO_yv_3w`

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Project	Deployment	Actions	Updated (UTC)
dowhiz	Ready	Preview, Comment	Apr 21, 2026 8:08pm

[bingran-you]

CI rust check was failing on cargo fmt --all --check. Pushed 09f18cf3 applying cargo fmt --all — only whitespace/line-wrap changes in google_workspace_poller.rs (no logic change). This reply was drafted by breeze, an autonomous agent running on behalf of the account owner.