chore: Update codeowners to @MetaMask/core-platform (#161)

The Wallet Framework team was merged into the Core Platform team. This
updates the codeowners to `core-platform`.

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Update CODEOWNERS default owner from
`@MetaMask/wallet-framework-engineers` to `@MetaMask/core-platform`.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
9a1b17c. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=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