Loosen stats validation for CLI

[wojtekn]

Related issues

• Fixes STU-732

Proposed Changes

I propose to fix CLI preview site creation by relaxing the Zod schema for lastBumpStats to accept arbitrary metric keys, preventing parse failures on older stat names like studio-app-launch-uniques-monthly.

Testing Instructions

1. Ensure you're authenticated in Studio (Sync, pull, push, assistant should work)
2. Try to create a preview site for any existing site
3. Verify the preview site creation completes without the "Invalid Studio config file format" error
4. Confirm the preview site appears in the previews tab and is accessible

To reproduce the issue in trunk, ensure to add an incorrect stat to appdata config files before launching Studio e.g.:

"lastBumpStats": {
    "studio-cli-usage-unique": {
      "success": 1747138805686
    },
    "studio-app-launch-uniques": {
      "darwin": 1755617494935
    },
    "studio-app-launch-uniques-monthly": {
      "darwin": 1754296649792
    },
    "studio-app-launch-uniqs-mon": {
      "darwin": 1754924827013
    }
  },

Pre-merge Checklist

• Have you checked for TypeScript, React or other console errors?

[gcsecsey]

This looks good and works as described. 👍

I confirm that with these changes and with the older stat names added to the config, I can create the Preview site and don't receive any errors. The preview site also works as expected.

No preview sites	Creating a preview site	Done