fix(web): name plugin detail close action

[lyzno1]

Summary

• Give the icon-only plugin detail panel close action the existing localized common.operation.close accessible name.
• Keep the close icon hidden from the accessibility tree because the button owns the action semantics.
• Make the owner test mock forward native button attributes and select Close by role and name instead of data-testid.

Behavior contract

• Assistive technology identifies the detail panel action as Close.
• Activating Close still calls the existing onHide callback.
• Update and all other plugin detail header behavior remain unchanged.

Visual regression

No visual change is expected. This PR does not change the rendered element, icon, classes, styles, layout, dimensions, node order, visibility, event handlers, or focus styling; it only adds an ARIA attribute.

Validation

• pnpm exec vp check app/components/plugins/plugin-detail-panel/detail-header/index.tsx app/components/plugins/plugin-detail-panel/detail-header/tests/index.spec.tsx (0 errors, 1 pre-existing warning)
• node scripts/lint-a11y.mjs app/components/plugins/plugin-detail-panel/detail-header/index.tsx (0 errors)
• pnpm exec vp test run app/components/plugins/plugin-detail-panel/detail-header/tests/index.spec.tsx (2/2)
• pnpm check (0 errors, 2059 existing warnings)

From Codex

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.42%. Comparing base (e036075) to head (0616a4a).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #40264   +/-   ##
=======================================
  Coverage   86.41%   86.42%           
=======================================
  Files        5107     5107           
  Lines      290731   290750   +19     
  Branches    57917    57923    +6     
=======================================
+ Hits       251245   251268   +23     
+ Misses      34545    34541    -4     
  Partials     4941     4941           

Flag	Coverage Δ
dify-ui	93.49% <ø> (ø)
web	86.11% <100.00%> (+<0.01%)	⬆️

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