fix: remove legacy deletions.jsonl from git tracking

The deletions.jsonl file contained merge conflicts and was causing
bd init/reset failures on fresh clones. Since we've migrated to
tombstones, these files are no longer needed.

Fixes GH#590

Co-Authored-By: Matt Wilkie <maphew@gmail.com>

🤖 Generated with Claude Code

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.beads/.gitignore

@@ -18,6 +18,10 @@ bd.sock
 db.sqlite
 bd.db
 
+# Legacy deletions manifest (replaced by tombstones)
+deletions.jsonl
+deletions.jsonl.migrated
+
 # Merge artifacts (temporary files from 3-way merge)
 beads.base.jsonl
 beads.base.meta.json
@@ -30,5 +34,3 @@ beads.right.meta.json
 !issues.jsonl
 !metadata.json
 !config.json
-deletions.jsonl
-deletions.jsonl.migrated