chore(db): move db/connectors/ to tooling/db/ (#274)

Consolidates all connector scripts under tooling/ per project
structure conventions. Symlink at db/connectors → tooling/db/
preserves backwards compatibility (remove after Sprint 22).

Updated references in CLAUDE.md, Makefile, DEVOPS.md, all skill
files, agent files, rules, schema comments, and Sprint 21
briefings. Python scripts updated with correct SCHEMA_PATH
(now relative to WORKTREE_ROOT/db/schema.sql).

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

tooling/db/sqlite-exec

@@ -0,0 +1,4 @@
+#!/usr/bin/env bash
+# Run an INSERT/UPDATE/DELETE on the ticketing database. Whitelistable command.
+# Usage: sqlite-exec "UPDATE tickets SET status='done' WHERE id=1"
+exec python3 "$(dirname "$0")/sqlite_connector.py" execute "$@"