Port bun-mariadb conventions: init globals, db handler, split schema sync

- init() loads config, schema and the SQLite client once into globals
- all CRUD queries go through lib/db-handler.ts (optional per-call config)
- split db-schema-manager.ts into lib/schema/* with FK-aware table ordering
- add bun:test tests for schema ordering, FK constraints and schema sync
- config/schema files can be .ts/.js/.json/.yaml/.yml; db_schema_file_name
  is now optional (defaults to schema.* in db_dir)
- add export/import commands (database snapshot + schema archives)
- package exports map, type re-exports, hardened publish.sh
- validate table name in delete

Co-Authored-By: Claude Opus 5.5 <[email protected]>

tsconfig.json

@@ -21,8 +21,9 @@
         "maxNodeModuleJsDepth": 10,
         "forceConsistentCasingInFileNames": true,
         "incremental": true,
+        "rootDir": "src",
         "outDir": "dist"
     },
     "include": ["src"],
-    "exclude": ["node_modules", "dist"]
+    "exclude": ["node_modules", "dist", "src/**/*.test.ts"]
 }