chore: Update codeowners to MetaMask/core-platform (#118)

Wallet Framework is now Core Platform.

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Low Risk**
> Only changes GitHub review routing metadata; no application or runtime
code is affected.
> 
> **Overview**
> Updates the repository-wide default in **`.github/CODEOWNERS`** so the
catch-all `*` pattern now requests review from
**`@MetaMask/core-platform`** instead of
**`@MetaMask/wallet-framework-engineers`**, matching the team rename
(Wallet Framework → Core Platform).
> 
> <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit
798da27. Bugbot is set up for automated
code reviews on this repo. Configure
[here](https://www.cursor.com/dashboard/bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: Mrtenz

.github/CODEOWNERS

@@ -1,4 +1,4 @@
 # Lines starting with '#' are comments.
 # Each line is a file pattern followed by one or more owners.
 
-*                                   @MetaMask/wallet-framework-engineers
+* @MetaMask/core-platform