chore: untrack large data files, certs, and worktree refs

Remove from git tracking (kept locally):
- docs/ data files (csv, cql, parquet ~38MB)
- stores.csv from examples/ and tests/
- global-bundle.pem, data.arrow
- .claude/worktrees/ refs

Updated .gitignore to prevent re-adding.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: phenobarbital

.claude/worktrees/feat-001-exception-migration

@@ -165,4 +165,14 @@ asyncdb/_version.py
 activities.csv
 *.csv
 examples/internals/test_db.py
-examples/test_elastic.py
+examples/test_elastic.py
+
+# Large data files
+data.arrow
+*.parquet
+
+# Certificates
+global-bundle.pem
+
+# Claude worktree refs
+.claude/worktrees/