Upgrade WordPress Playground and PHP WASM to 3.1.2

[epeicher]

Related issues

• Fixes STU-73

Proposed Changes

• Upgrade @wp-playground/* packages from 3.1.1 to 3.1.2
• Upgrade @php-wasm/universal and related packages from 3.1.1 to 3.1.2
• Update patch file for @wp-playground/wordpress to match 3.1.2 release
• Update fast-xml-parser dependency to 5.3.7

Testing Instructions

• Apply these changes and run npm install
• Start Studio and create a site larger than 2GB, you can add many big images to the Media
• Open wp-admin and install All in One migration plugin
• Using the plugin, export the site to a file

• Check that you can download the file

Regression testing

• Verify that Studio works as expected for creating/starting/stopping and deleting sites, and some smoke testing.

Pre-merge Checklist

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

[wpmobilebot]

📊 Performance Test Results

Comparing d4b20d5 vs trunk

site-editor

Metric	trunk	d4b20d5	Diff	Change
load	1438.00 ms	1524.00 ms	+86.00 ms	🔴 6.0%

site-startup

Metric	trunk	d4b20d5	Diff	Change
siteCreation	8117.00 ms	7142.00 ms	-975.00 ms	🟢 -12.0%
siteStartup	4940.00 ms	4949.00 ms	+9.00 ms	⚪ 0.0%

---

Results are median values from multiple test runs.

Legend: 🟢 Improvement (faster) | 🔴 Regression (slower) | ⚪ No change (<50ms diff)

[epeicher]

Closing this in favor of #2643