Add comprehensive unit tests for the compact package:
- haiku.go: Mock API tests for SummarizeTier1, retry logic tests for
callWithRetry (429/500 handling, exhaust retries, context timeout),
expanded isRetryable tests for network timeouts and API error codes
- git.go: Tests for GetCurrentCommitHash in various git states
(in repo, outside repo, new repo, empty repo)
- compactor.go: Unit tests for New(), CompactTier1(), CompactTier1Batch()
with mock API server, config validation, error paths
Small production change: NewHaikuClient now accepts variadic options
for testing (option.WithBaseURL, option.WithMaxRetries).
Coverage: 17.3% → 81.8%
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
