refactor(ui): use inset ring utilities

[lyzno1]

Summary

• replace self-contained ring-* + ring color + ring-inset class groups with Tailwind v4 inset-ring-* utilities
• leave modifier-only ring-inset call sites unchanged when width/color come from an upstream component or dynamic class composition
• remove unit tests that only asserted cosmetic ring utility class names

Rationale

Tailwind v4 exposes inset ring utilities directly, so static inset ring groups can use the narrower utility pair without changing the rendered focus or selection treatment. Tests should not lock this kind of utility spelling; behavior and accessibility tests remain in place.

Validation

• pnpm exec eslint --fix $(git diff --name-only | tr '\n' ' ')
• pnpm --filter @langgenius/dify-ui test -- src/select/__tests__/index.spec.tsx src/segmented-control/__tests__/index.spec.tsx
• pnpm -C web test app/components/app-sidebar/app-info/__tests__/app-operations.spec.tsx app/components/base/chip/__tests__/index.spec.tsx app/components/base/file-uploader/file-uploader-in-chat-input/__tests__/index.spec.tsx app/components/base/search-input/__tests__/index.spec.tsx app/components/datasets/list/dataset-card/components/__tests__/operations-dropdown.spec.tsx app/components/develop/__tests__/md.spec.tsx app/components/develop/__tests__/tag.spec.tsx app/components/explore/app-card/__tests__/index.spec.tsx app/components/explore/sidebar/app-nav-item/__tests__/index.spec.tsx app/components/integrations/__tests__/tool-provider-list.spec.tsx features/agent-v2/roster/components/__tests__/agent-roster-list.spec.tsx
• pnpm -C web type-check
• pnpm --filter @langgenius/dify-ui type-check
• PostCSS/Tailwind compile check for web/app/styles/globals.css
• git diff --check

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.35%. Comparing base (bf46b82) to head (02844c2).

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #38275      +/-   ##
==========================================
- Coverage   85.35%   85.35%   -0.01%     
==========================================
  Files        4981     4981              
  Lines      262024   262024              
  Branches    49606    49606              
==========================================
- Hits       223662   223660       -2     
- Misses      33978    33980       +2     
  Partials     4384     4384              

Flag	Coverage Δ
dify-ui	94.93% <ø> (ø)
web	85.07% <100.00%> (-0.01%)	⬇️

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