fix(web): expose debug toolbar semantics

[lyzno1]

Summary

• Give the debug toolbar restart and user-input-panel actions explicit accessible names using their existing tooltip translations.
• Expose the user-input panel toggle state through aria-expanded.
• Hide decorative toolbar icons from the accessibility tree.
• Make the ActionButton test double forward native button attributes, then replace index-based test-id queries with role, name, and state assertions.

Behavior contract

• Assistive technology identifies the toolbar actions as Restart and User Input Field.
• Restart still resets the single-model conversation and remains available for readonly apps with test/run permission.
• The user-input action reports its expanded or collapsed state and still shows or hides the existing input panel.
• Permission-gated absence remains covered.

Visual regression

No visual change is expected. This PR does not change elements, classes, styles, layout, node order, tooltip content, or event handlers; it only adds ARIA attributes and strengthens the owner test boundary.

The existing icon migration warnings and debug owner's existing data-flow lint debt are intentionally left unchanged for separate review.

Validation

• node scripts/lint-a11y.mjs app/components/app/configuration/debug/index.tsx
• pnpm exec vp test run app/components/app/configuration/debug/tests/index.spec.tsx (28/28)
• pnpm check (0 errors, 2059 existing warnings)

The narrow file-only lint command also reports thirteen pre-existing baseline errors across this large owner and its test; this PR introduces none of those diagnostics.

From Codex

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.42%. Comparing base (e036075) to head (ab0797f).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #40258   +/-   ##
=======================================
  Coverage   86.41%   86.42%           
=======================================
  Files        5107     5107           
  Lines      290731   290751   +20     
  Branches    57917    57923    +6     
=======================================
+ Hits       251245   251272   +27     
+ Misses      34545    34538    -7     
  Partials     4941     4941           

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

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.