fix(calendar): M1 — propagate Google pull-side updates and deletes

[h4yfans]

Summary

Milestone 1 of Google Calendar Phase 2. Fixes three correctness bugs in the Google pull loop so Google-side updates, deletions, and cursor-invalidation reach bound Memry records.

• Route bound-remote updates through applyGoogleCalendarWriteback (previously never invoked by the pull loop)
• Propagate Google cancellations through applyGoogleCalendarDelete (previously dropped)
• Archive the mirror row when an unbound Google event is cancelled + skip phantom materialization for never-seen cancellations
• Defensive 410 Gone handling around client.listEvents — insurance for future client variants; see docs commit for why current path is dormant

No schema changes, no new IPC surface, no renderer changes.

Design: .claude/plans/2026-04-18-google-calendar-phase-2-design.md
Plan: .claude/plans/2026-04-18-google-calendar-phase-2-m1-correctness.md

Test plan

• Unit: findCalendarBindingByRemoteEvent returns the active binding and skips archived ones
• Integration: bound Google update writes through to native calendar_events row; mirror stays empty; binding etag refreshed
• Integration: bound Google cancellation deletes the native row and archives the binding
• Integration: unbound Google cancellation archives the existing mirror row
• Integration: unbound Google cancellation with no pre-existing mirror does NOT materialize a phantom archived row
• Integration: 410 Gone on listEvents clears syncCursor and retries with null
• Full pnpm --filter @memry/desktop exec vitest run green
• pnpm typecheck:node and pnpm typecheck:web clean (modulo known pre-existing test-file errors called out in CLAUDE.md)
• pnpm lint clean