refactor: improve model selector search

[lyzno1]

Summary

• refactor ModelSelector around controlled combobox state so only real provider/model options participate in the selection collection
• keep marketplace, empty state, compatibility notice, and settings footer outside listbox option semantics
• add Fuse-backed provider search and normalized model search for precise model ID matching
• add regression coverage for provider fuzzy matching, namespaced provider keys, and model ID queries such as gpt5.4

Commits

• 87a01a0 refactor: model selector
• 8896c35 feat: improve model selector search

Part of #35867

Tests

• pnpm --dir web test app/components/header/account-setting/model-provider-page/model-selector/tests/popup.spec.tsx
• pnpm --dir web type-check
• pnpm exec eslint web/app/components/header/account-setting/model-provider-page/model-selector/index.tsx web/app/components/header/account-setting/model-provider-page/model-selector/popup.tsx web/app/components/header/account-setting/model-provider-page/model-selector/popup-item.tsx web/app/components/header/account-setting/model-provider-page/model-selector/model-search.ts web/app/components/header/account-setting/model-provider-page/model-selector/tests/popup.spec.tsx

[codecov]

Codecov Report

❌ Patch coverage is 94.93671% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.82%. Comparing base (1e2d309) to head (7ea4d6c).

Files with missing lines	Patch %	Lines
...tting/model-provider-page/model-selector/index.tsx	81.25%	6 Missing ⚠️
...model-provider-page/model-selector/model-search.ts	97.14%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #35875      +/-   ##
==========================================
- Coverage   85.82%   85.82%   -0.01%     
==========================================
  Files        4460     4462       +2     
  Lines      209092   209147      +55     
  Branches    39112    39126      +14     
==========================================
+ Hits       179461   179508      +47     
- Misses      26455    26463       +8     
  Partials     3176     3176              

Flag	Coverage Δ
dify-ui	93.93% <ø> (ø)
web	86.77% <94.93%> (-0.01%)	⬇️

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