Upgrade Claude model configuration from dual-key to quad-key system for
better model tier differentiation.
**Breaking Changes:**
- Replace `ANTHROPIC_SMALL_FAST_MODEL` with three granular keys:
- `ANTHROPIC_DEFAULT_HAIKU_MODEL`
- `ANTHROPIC_DEFAULT_SONNET_MODEL`
- `ANTHROPIC_DEFAULT_OPUS_MODEL`
**Backend (Rust):**
- Add `normalize_claude_models_in_value()` for automatic migration
- Implement fallback chain: `DEFAULT_* || SMALL_FAST || MODEL`
- Auto-cleanup: remove legacy `SMALL_FAST` key after normalization
- Apply normalization across 6 critical paths:
- Add/update provider
- Read from live config
- Write to live config
- Refresh config snapshot
**Frontend (React):**
- Expand UI from 2 to 4 model input fields
- Implement smart fallback in `useModelState` hook
- Update `useKimiModelSelector` for Kimi model picker
- Add i18n keys for Haiku/Sonnet/Opus labels (zh/en)
**Configuration:**
- Update all 7 provider presets to new format
- DeepSeek/Qwen/Moonshot: use same model for all tiers
- Zhipu: preserve tier differentiation (glm-4.5-air for Haiku)
**Backward Compatibility:**
- Old configs auto-upgrade on first read/write
- Fallback chain ensures graceful degradation
- No manual migration required
Closes #[issue-number]
- Create custom hooks for state management:
- useProviderCategory: manages provider category state
- useApiKeyState: manages API key input with auto-sync to config
- useBaseUrlState: manages base URL for Claude and Codex
- useModelState: manages model selection state
- Integrate API key input into simplified ProviderForm:
- Add ApiKeyInput component for Claude mode
- Auto-populate API key into settings config
- Disable for official providers
- Fix EndpointSpeedTest type errors:
- Fix import paths to use @ alias
- Add temporary type definitions
- Format all TODO comments properly
- Remove incorrect type assertions
- Comment out unimplemented window.api checks
All TypeScript type checks now pass.
Jason