Fix media modal crash on WP 7.0 due to attachment filters wrapper change

[kraftbj]

WP core commit 61757 wrapped the media attachment filters <select> and <label> in a container <div> for accessibility. This changed toolbar.get('filters') from returning the AttachmentFilters view directly to returning a wrapper wp.media.View, causing customizeFilters() to crash with:

Uncaught TypeError: Cannot read properties of undefined (reading 'all')
    at n.customizeFilters

This broke the media modal for any SCF image/file field on WP 7.0.

The fix resolves the actual AttachmentFilters view by checking whether the returned view has a .filters property. If not (WP 7.0+), it traverses the wrapper's subviews to find the AttachmentFilters instance. This is compatible with both WP < 7.0 and WP 7.0+.

Tested on both WP 6.9.4 and WP 7.0-RC2 with the full E2E suite passing.

Fixes #396
See https://core.trac.wordpress.org/ticket/64948

Use of AI Tools

This PR was authored with assistance from Claude Code (Anthropic). The fix was developed after debugging the root cause using Playwright-based investigation of the media modal behavior on WP 7.0-RC2.

[github-actions]

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Props kraftbj, bernhard-reiter.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 52.65%. Comparing base (b448e17) to head (e6c450e).
⚠️ Report is 2 commits behind head on trunk.

Additional details and impacted files

@@             Coverage Diff              @@
##              trunk     #399      +/-   ##
============================================
- Coverage     54.00%   52.65%   -1.35%     
  Complexity     4423     4423              
============================================
  Files           298      298              
  Lines         39467    39475       +8     
============================================
- Hits          21314    20786     -528     
- Misses        18153    18689     +536     

Flag	Coverage Δ
e2e-js	45.76% <100.00%> (+0.03%)	⬆️
e2e-php	40.58% <ø> (-2.15%)	⬇️
javascript	15.06% <0.00%> (-0.02%)	⬇️
phpunit	29.95% <ø> (ø)

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