Add EventCompacted to event system (bd-262)

- Add EventCompacted event type constant
- Add compaction fields to Issue struct (CompactionLevel, CompactedAt, OriginalSize)
- Update ApplyCompaction to record compaction events with JSON metadata
- Update bd show to display compaction status with emoji indicators
- Update GetIssue query to load compaction fields
- All tests passing

Amp-Thread-ID: https://ampcode.com/threads/T-3f7946c6-8f5e-4a81-9527-1217041c7b39
Co-authored-by: Amp <amp@ampcode.com>

.beads/issues.jsonl

@@ -178,7 +178,7 @@
 {"id":"bd-26","title":"Optimize reference updates to avoid loading all issues into memory","description":"In updateReferences(), we call SearchIssues with no filter to get ALL issues for updating references. For large databases (10k+ issues), this loads everything into memory. Options: 1) Use batched processing with LIMIT/OFFSET, 2) Use SQL UPDATE with REPLACE() directly, 3) Stream results instead of loading all at once. Located in collision.go:266","status":"open","priority":2,"issue_type":"task","created_at":"2025-10-14T14:43:06.911497-07:00","updated_at":"2025-10-15T16:27:22.001829-07:00"}
 {"id":"bd-260","title":"Add `bd compact --restore` functionality","description":"Implement restore command to undo compaction from snapshots.","design":"Add to `cmd/bd/compact.go`:\n\n```go\nvar compactRestore string\n\ncompactCmd.Flags().StringVar(\u0026compactRestore, \"restore\", \"\", \"Restore issue from snapshot\")\n```\n\nProcess:\n1. Load snapshot for issue\n2. Parse JSON content\n3. Update issue with original content\n4. Set compaction_level = 0, compacted_at = NULL, original_size = NULL\n5. Record event (EventRestored or EventUpdated)\n6. Mark dirty for export","acceptance_criteria":"- Restores exact original content\n- Handles multiple snapshots (use latest by default)\n- `--level` flag to choose specific snapshot\n- Updates compaction_level correctly\n- Exports restored content to JSONL\n- Shows before/after in output","notes":"Won't fix - snapshots defeat the purpose of compaction","status":"closed","priority":2,"issue_type":"task","created_at":"2025-10-15T21:51:23.240267-07:00","updated_at":"2025-10-16T00:26:13.913152-07:00","closed_at":"2025-10-16T00:26:13.913156-07:00","labels":["---","cli","compaction","restore"]}
 {"id":"bd-261","title":"Add `bd compact --stats` command","description":"Add statistics command showing compaction status and potential savings.","design":"```go\nvar compactStats bool\n\ncompactCmd.Flags().BoolVar(\u0026compactStats, \"stats\", false, \"Show compaction statistics\")\n```\n\nOutput:\n- Total issues, by compaction level (0, 1, 2)\n- Current DB size vs estimated uncompacted size\n- Space savings (KB/MB and %)\n- Candidates for each tier with size estimates\n- Estimated API cost (Haiku pricing)","acceptance_criteria":"- Accurate counts by compaction_level\n- Size calculations include all text fields (UTF-8 bytes)\n- Shows candidates with eligibility reasons\n- Cost estimation based on current Haiku pricing\n- JSON output supported\n- Clear, readable table format","status":"closed","priority":2,"issue_type":"task","created_at":"2025-10-15T21:51:23.242041-07:00","updated_at":"2025-10-16T00:26:06.624041-07:00","closed_at":"2025-10-16T00:26:06.624041-07:00","labels":["---","compaction","reporting","stats"]}
-{"id":"bd-262","title":"Add EventCompacted to event system","description":"Add new event type for tracking compaction in audit trail.","design":"1. Add to `internal/types/types.go`:\n```go\nconst EventCompacted EventType = \"compacted\"\n```\n\n2. Record event during compaction:\n```go\neventData := map[string]interface{}{\n    \"tier\": tier,\n    \"original_size\": originalSize,\n    \"compressed_size\": compressedSize,\n    \"reduction_pct\": (1 - float64(compressedSize)/float64(originalSize)) * 100,\n}\n```\n\n3. Update event display in `bd show`.","acceptance_criteria":"- Event includes tier, original_size, compressed_size, reduction_pct\n- Shows in event history (`bd events \u003cid\u003e`)\n- Exports to JSONL correctly\n- `bd show` displays compaction status and marker","status":"open","priority":2,"issue_type":"task","created_at":"2025-10-15T21:51:23.244219-07:00","updated_at":"2025-10-15T21:51:23.244219-07:00","labels":["---","audit","compaction","events"]}
+{"id":"bd-262","title":"Add EventCompacted to event system","description":"Add new event type for tracking compaction in audit trail.","design":"1. Add to `internal/types/types.go`:\n```go\nconst EventCompacted EventType = \"compacted\"\n```\n\n2. Record event during compaction:\n```go\neventData := map[string]interface{}{\n    \"tier\": tier,\n    \"original_size\": originalSize,\n    \"compressed_size\": compressedSize,\n    \"reduction_pct\": (1 - float64(compressedSize)/float64(originalSize)) * 100,\n}\n```\n\n3. Update event display in `bd show`.","acceptance_criteria":"- Event includes tier, original_size, compressed_size, reduction_pct\n- Shows in event history (`bd events \u003cid\u003e`)\n- Exports to JSONL correctly\n- `bd show` displays compaction status and marker","status":"closed","priority":2,"issue_type":"task","created_at":"2025-10-15T21:51:23.244219-07:00","updated_at":"2025-10-16T00:59:17.465182-07:00","closed_at":"2025-10-16T00:59:17.465182-07:00","labels":["---","audit","compaction","events"]}
 {"id":"bd-263","title":"Add compaction indicator to `bd show`","description":"Update `bd show` command to display compaction status prominently.","design":"Add to issue display:\n```\nbd-42: Fix authentication bug [CLOSED] 🗜️\n\nStatus: closed (compacted L1)\n...\n\n---\n💾 Restore: bd compact --restore bd-42\n📊 Original: 2,341 bytes | Compressed: 468 bytes (80% reduction)\n🗜️ Compacted: 2025-10-15 (Tier 1)\n```\n\nEmoji indicators:\n- Tier 1: 🗜️\n- Tier 2: 📦","acceptance_criteria":"- Compaction status visible in title line\n- Footer shows size savings when compacted\n- Restore command shown for compacted issues\n- Works with `--json` output (includes compaction fields)\n- Emoji optional (controlled by config or terminal detection)","status":"open","priority":2,"issue_type":"task","created_at":"2025-10-15T21:51:23.253091-07:00","updated_at":"2025-10-15T21:51:23.253091-07:00","labels":["---","compaction","display","ui"]}
 {"id":"bd-264","title":"Write compaction tests","description":"Comprehensive test suite for compaction functionality.","design":"Test coverage:\n\n1. **Candidate Identification:**\n   - Eligibility by time\n   - Dependency depth checking\n   - Mixed status dependents\n   - Edge cases (no deps, circular deps)\n\n2. **Snapshots:**\n   - Create and restore\n   - Multiple snapshots per issue\n   - Content integrity (UTF-8, special chars)\n\n3. **Tier 1 Compaction:**\n   - Single issue compaction\n   - Batch processing\n   - Error handling (API failures)\n\n4. **Tier 2 Compaction:**\n   - Requires Tier 1\n   - Events pruning\n   - Commit counting fallback\n\n5. **CLI:**\n   - All flag combinations\n   - Dry-run accuracy\n   - JSON output parsing\n\n6. **Integration:**\n   - End-to-end flow\n   - JSONL export/import\n   - Restore verification","acceptance_criteria":"- Test coverage \u003e80%\n- All edge cases covered\n- Mock Haiku API in tests (no real API calls)\n- Integration tests pass\n- `go test ./...` passes\n- Benchmarks for performance-critical paths","status":"closed","priority":1,"issue_type":"task","created_at":"2025-10-15T21:51:23.262504-07:00","updated_at":"2025-10-16T00:02:11.246331-07:00","closed_at":"2025-10-16T00:02:11.246331-07:00","labels":["---","compaction","quality","testing"]}
 {"id":"bd-265","title":"Add compaction documentation","description":"Document compaction feature in README and create detailed COMPACTION.md guide.","design":"**Update README.md:**\n- Add to Features section\n- CLI examples (dry-run, compact, restore, stats)\n- Configuration guide\n- Cost analysis\n\n**Create COMPACTION.md:**\n- How compaction works (architecture overview)\n- When to use each tier\n- Detailed cost analysis with examples\n- Safety mechanisms (snapshots, restore, dry-run)\n- Troubleshooting guide\n- FAQ\n\n**Create examples/compaction/:**\n- `workflow.sh` - Example monthly compaction workflow\n- `cron-compact.sh` - Cron job setup\n- `auto-compact.sh` - Auto-compaction script","acceptance_criteria":"- README.md updated with compaction section\n- COMPACTION.md comprehensive and clear\n- Examples work as documented (tested)\n- Screenshots or ASCII examples included\n- API key setup documented (env var vs config)\n- Covers common questions and issues","status":"open","priority":2,"issue_type":"task","created_at":"2025-10-15T21:51:23.265589-07:00","updated_at":"2025-10-15T21:51:23.265589-07:00","labels":["---","compaction","docs","documentation","examples"]}