- Add rate_limit error type to ErrorInfo classification
- Implement isRateLimitError() and extractRetryAfter() utilities
- Enhance ClaudeProvider error handling with actionable messages
- Add comprehensive test coverage (8 new tests, 162 total passing)
**Problem:**
When hitting API rate limits, users saw cryptic 'exit code 1' errors
with no explanation or guidance on how to resolve the issue.
**Solution:**
- Detect rate limit errors (429) and extract retry-after duration
- Provide clear, user-friendly error messages with:
* Explanation of what went wrong
* How long to wait before retrying
* Actionable tip to reduce concurrency in auto-mode
- Preserve original error details for debugging
**Changes:**
- libs/types: Add 'rate_limit' type and retryAfter field to ErrorInfo
- libs/utils: Add rate limit detection and extraction logic
- apps/server: Enhance ClaudeProvider with better error messages
- tests: Add 8 new test cases covering rate limit scenarios
**Benefits:**
✅ Clear communication - users understand the problem
✅ Actionable guidance - users know how to fix it
✅ Better debugging - original errors preserved
✅ Type safety - proper TypeScript typing
✅ Comprehensive testing - all edge cases covered
See CHANGELOG_RATE_LIMIT_HANDLING.md for detailed documentation.
