feat(database): refactor CLI, add column whitelist, and SSL config

- Add `ZEN_DB_SSL_DISABLED` env variable to allow disabling SSL for database connections
- Refactor database CLI to split init logic into `initFeatures` and `initModules` for modular table initialization, with graceful fallback when modules are absent
- Extract `printHelp` and `askConfirmation` helpers for cleaner CLI structure
- Ensure `closePool` is called on both success and error paths in CLI
- Add `filterAllowedColumns` utility in `crud.js` to enforce column whitelists, preventing mass-assignment of privileged fields (e.g. `role`, `email_verified`)
- Update drop command description from "auth tables" to "all tables"

src/features/features.registry.js

@@ -0,0 +1,13 @@
+/**
+ * Core Features Registry
+ *
+ * Lists all built-in features that are always initialized when running `zen-db init`.
+ * Unlike optional modules (src/modules), core features are not gated by env vars —
+ * they are required for the application to function.
+ *
+ * Each name must correspond to a directory under src/features/ that exposes a db.js
+ * with createTables() and optionally dropTables().
+ */
+export const CORE_FEATURES = [
+  'auth',
+];