fix(menubar): clamp unsafe Antigravity token counts

[ozymandiashh]

Addresses #515.

This hardens the Antigravity ingestion path so unsafe or unstable token counts cannot break the menubar payload or Swift decoding.

What changed:

• Parse Antigravity token counts through a safe integer path, including safe numeric strings and bigints, while rejecting unsafe, negative, fractional, and malformed values.
• Preserve output-only and split-output metadata correctly, including the case where total output is present, thinking output is present, and response output is omitted.
• Add a final token-sanitization pass before menubar JSON emission.
• Make the Swift menubar payload decoder tolerant for token fields while keeping non-token fields strict.
• Invalidate stale Antigravity caches after the token-safety change and include SQLite -wal / -shm sidecars in the DB cache fingerprint.

Validation:

• npm test -- tests/providers/antigravity.test.ts tests/session-cache.test.ts tests/daily-cache.test.ts tests/menubar-json.test.ts --run — 127 passing
• npx tsc --noEmit
• npm run build
• cd mac && swift build

[ozymandiashh]

Updated after the cache-preservation review pass.

One extra edge case is now covered: if an existing session-cache.json contains an unsafe Antigravity token count, loadCache() now drops only the invalid provider/file section and preserves valid sections such as durable Copilot cache entries. That avoids losing durable telemetry while still flushing the corrupt Antigravity data.

Validation after the update:

• npm test -- tests/session-cache.test.ts tests/providers/antigravity.test.ts tests/menubar-json.test.ts tests/daily-cache.test.ts --run — 134 tests passed
• npx tsc --noEmit — passed
• cd mac && swift build — passed
• git diff --check — passed

PR is mergeable and current checks are green.