- Use PDF icon via systray.SetIcon for sharp 4K display support
- Fall back to PNG template icons if PDF unavailable
- Add thin space between icon and text in tray display
- Add icon_test.go with PDF/PNG validation tests

Co-Authored-By: Claude Opus 4.6 <[email protected]>

Add OpenRouter as a new provider for tracking API credit usage,
daily/weekly/monthly spending, and rate limits.

Polls GET /api/v1/auth/key for usage data including:
- Total usage (USD)
- Daily/weekly/monthly usage breakdowns
- Credit limit and remaining balance (when configured)
- Rate limit info
- Free tier detection

Implementation follows the existing provider pattern (Z.ai/MiniMax):
- internal/api/openrouter_client.go: HTTP client with Bearer auth
- internal/api/openrouter_types.go: Response structs and snapshot type
- internal/store/openrouter_store.go: SQLite storage and cycle tracking
- internal/tracker/openrouter_tracker.go: Delta tracking and projections
- internal/agent/openrouter_agent.go: Polling agent

Integration points:
- Config: OPENROUTER_API_KEY env var
- Dashboard: Provider tab with usage cards and charts
- Auto-detection: Uses env var (no local auth file)

Env var: OPENROUTER_API_KEY

macOS systray works better with PNG template/retina icons than PDF.
Remove PDF icon support and associated tests.

Co-Authored-By: Claude Opus 4.6 <[email protected]>

feat: use PDF vector icon for crisp menubar rendering

fix: add explicit expiry to login session cookie

Fix: Copilot quota tracking for free/limited plans

feat: add OpenRouter provider for credit/usage monitoring

…dels

- Add OpenRouter provider detection in getCurrentProvider() JS function
- Add OpenRouter Credits quota card with dynamic rendering
- Add OpenRouter to chart initialization, history rendering, and cycle overview
- Add OpenRouter to menubar provider cards and settings dropdown
- Add 'credits' to renewalCategories and quota display names
- Filter out MiniMax models with zero quota (total=0, used=0) from
  current view, history charts, logging history, tracker, and menubar
- Strip non-chart fields (isFreeTier, limit, remaining) from OpenRouter
  history response to clean up chart legends
- Update README with OpenRouter setup instructions

fix: OpenRouter frontend + MiniMax zero-quota filter

When the OAuth refresh endpoint returns 429, the agent now enters
exponential backoff (5min base, doubling to 6h cap) instead of
retrying every poll cycle. This prevents burning one-time-use refresh
tokens which could invalidate Claude Code sessions.

- Add ErrOAuthRateLimited and ErrOAuthInvalidGrant sentinel errors
- Add rateLimitFailCount/rateLimitPaused/rateLimitResumeAt state
- Protect both proactive refresh and 429 bypass paths with shared backoff
- Auto-resume on credential change or backoff expiry
- invalid_grant triggers terminal pause (like auth errors)