feat: implement 5 CLI-IMP beads — hybrid search, robot-docs, data gaps, drift, skill rewrite

Wire hybrid search (FTS5 + vector + RRF) to CLI search command.
Enhance robot-docs with quick_start guide and example_output.
Fill data gaps in issue detail (references, note counts, closed_at).
Add lore drift command for discussion divergence detection.
Rewrite agent skills to mandate lore for reads, glab for writes.

Closes: bd-1ksf, bd-91j1, bd-2g50, bd-1cjx, bd-kvij

migrations/023_issue_detail_fields.sql

@@ -0,0 +1,5 @@
+ALTER TABLE issues ADD COLUMN closed_at TEXT;
+ALTER TABLE issues ADD COLUMN confidential INTEGER NOT NULL DEFAULT 0;
+
+INSERT INTO schema_version (version, applied_at, description)
+VALUES (23, strftime('%s', 'now') * 1000, 'Add closed_at and confidential to issues');