feat(db): decision ID claim system — prevent cross-worktree collisions

- `db/connectors/decision next [D|Q|R]` — show next available ID
- `db/connectors/decision claim <prefix> <domain> [title]` — reserve ID in DB
- `db/connectors/decision check-dupes` — detect duplicate IDs in markdown
- `tooling/check-decision-ids` — pre-commit hook for dupe detection
- D-035 added as known exception (139 files, too embedded to renumber)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.config/hooks/pre-commit

@@ -21,6 +21,7 @@ run_check() {
 
 # --- Checks ---
 run_check "tooling/check-fact-ids" "fact_id validation"
+run_check "tooling/check-decision-ids" "decision ID duplication"
 
 if [ "$ERRORS" -gt 0 ]; then
     echo ""