* feat: add thinking token tracking and historical analytics
- extractThinkingTokens(): separate thinking from output tokens
- TokenUsageTracker class for historical analytics
- Track: cache hit rate, most used model, requests per hour/day
- Analytics: average tokens per request, totals
- Add tests (7 passing)
PR 4B: Features 1.10 + 1.11
* refactor: extract thinking and analytics to separate files
- Create thinkingTokenExtractor.ts with ThinkingTokenAnalyzer
- Create tokenAnalytics.ts with TokenUsageTracker
- Add production-grade methods and tests
- Update test imports
