Fix P0 bug: JSONL lookup now returns LAST match (bd-58c0)

Addresses code review feedback:

✅ P0 (Must Fix):
- Fix JSONL lookup to return LAST match, not FIRST (resurrection.go:160-162)
  - Changed from early return to scan all matches and keep last
  - Respects JSONL append-only semantics

✅ P1 (Should Fix):
- Add test for multiple JSONL versions
  - TestTryResurrectParent_MultipleVersionsInJSONL verifies correct behavior
- Document error message change in CHANGELOG.md
  - Old: "parent issue X does not exist"
  - New: "parent issue X does not exist and could not be resurrected from JSONL history"
  - Marked as breaking change for script parsers

✅ P2/P3 (Nice to Have):
- Add documentation to AGENTS.md explaining auto-resurrection behavior
- Document best-effort dependency resurrection

⏸️ Deferred (P1 - Optimize batch resurrection):
- Caching optimization deferred (no batch use cases currently)

All tests pass:
- Unit tests: internal/storage/sqlite/
- Integration test: TestImportWithDeletedParent

AGENTS.md

@@ -213,6 +213,13 @@ bd import -i .beads/issues.jsonl --dry-run      # Preview changes
 bd import -i .beads/issues.jsonl                # Import and update issues
 bd import -i .beads/issues.jsonl --dedupe-after # Import + detect duplicates
 
+# Note: Import automatically handles missing parents!
+# - If a hierarchical child's parent is missing (e.g., bd-abc.1 but no bd-abc)
+# - bd will search the JSONL history for the parent
+# - If found, creates a tombstone placeholder (Status=Closed, Priority=4)
+# - Dependencies are also resurrected on best-effort basis
+# - This prevents import failures after parent deletion
+
 # Find and merge duplicate issues
 bd duplicates                                          # Show all duplicates
 bd duplicates --auto-merge                             # Automatically merge all