Add WP_DEBUG_LOG and WP_DEBUG_DISPLAY toggles

[bcotrim]

Related issues

Fixes #23

Proposed Changes

• Add WP_DEBUG_LOG and WP_DEBUG_DISPLAY toggles in a new "Developer" tab within the Edit Site modal
• Xdebug control moved to Developer tab alongside new debug toggles
• WP_DEBUG automatically enabled when either WP_DEBUG_LOG or WP_DEBUG_DISPLAY is toggled on
• Developer settings grouped in read-only Settings view
• Full CLI support: studio site set --debug-log --debug-display with --no- variants
• Server restart triggered when debug settings change

Testing Instructions

1. Open WordPress Studio and select a site
2. Click "Edit site" → Developer tab
3. Toggle "Enable debug log" and "Show errors in browser"
4. Save and verify the site restarts
5. Check that wp-content/debug.log is created
6. Via CLI: studio site set --path /path/to/site --debug-log --debug-display

Pre-merge Checklist

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

[wpmobilebot]

📊 Performance Test Results

Comparing 6f9d087 vs trunk

site-editor

Metric	trunk	6f9d087	Diff	Change
load	2744.00 ms	2771.00 ms	+27.00 ms	🔴 1.0%

site-startup

Metric	trunk	6f9d087	Diff	Change
siteCreation	7071.00 ms	7084.00 ms	+13.00 ms	🔴 0.2%
siteStartup	3922.00 ms	3927.00 ms	+5.00 ms	🔴 0.1%

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Results are median values from multiple test runs.

Legend: 🟢 Improvement (faster) | 🔴 Regression (slower) | ⚪ No change