refactor(models): migrate to granular model configuration architecture

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]

src/components/providers/forms/ProviderForm.tsx

@@ -140,12 +140,17 @@ export function ProviderForm({
     },
   });
 
-  // 使用 Model hook
-  const { claudeModel, claudeSmallFastModel, handleModelChange } =
-    useModelState({
-      settingsConfig: form.watch("settingsConfig"),
-      onConfigChange: (config) => form.setValue("settingsConfig", config),
-    });
+  // 使用 Model hook（新：主模型 + Haiku/Sonnet/Opus 默认模型）
+  const {
+    claudeModel,
+    defaultHaikuModel,
+    defaultSonnetModel,
+    defaultOpusModel,
+    handleModelChange,
+  } = useModelState({
+    settingsConfig: form.watch("settingsConfig"),
+    onConfigChange: (config) => form.setValue("settingsConfig", config),
+  });
 
   // 使用 Codex 配置 hook (仅 Codex 模式)
   const {
@@ -218,7 +223,9 @@ export function ProviderForm({
   const {
     shouldShow: shouldShowKimiSelector,
     kimiAnthropicModel,
-    kimiAnthropicSmallFastModel,
+    kimiDefaultHaikuModel,
+    kimiDefaultSonnetModel,
+    kimiDefaultOpusModel,
     handleKimiModelChange,
   } = useKimiModelSelector({
     initialData,
@@ -500,10 +507,14 @@ export function ProviderForm({
               category !== "official" && !shouldShowKimiSelector
             }
             claudeModel={claudeModel}
-            claudeSmallFastModel={claudeSmallFastModel}
+            defaultHaikuModel={defaultHaikuModel}
+            defaultSonnetModel={defaultSonnetModel}
+            defaultOpusModel={defaultOpusModel}
             onModelChange={handleModelChange}
             kimiAnthropicModel={kimiAnthropicModel}
-            kimiAnthropicSmallFastModel={kimiAnthropicSmallFastModel}
+            kimiDefaultHaikuModel={kimiDefaultHaikuModel}
+            kimiDefaultSonnetModel={kimiDefaultSonnetModel}
+            kimiDefaultOpusModel={kimiDefaultOpusModel}
             onKimiModelChange={handleKimiModelChange}
             speedTestEndpoints={speedTestEndpoints}
           />