fix: update database CLI entry point path

Move the database CLI entry point from `src/cli/database.js` to
`src/core/database/cli.js` to better reflect its location within
the core database module. Update both the `package.json` bin path
and `tsup.config.js` build entry accordingly.

package.json

@@ -23,7 +23,7 @@
     "prepublishOnly": "npm run build"
   },
   "bin": {
-    "zen-db": "./dist/cli/database.js"
+    "zen-db": "./dist/core/database/cli.js"
   },
   "dependencies": {
     "@headlessui/react": "^2.0.0",