revert: restore full config overwrite + Common Config Snippet (revert 992dda5c)

Revert the partial key-field merging refactoring introduced in 992dda5c,
along with two dependent commits (24fa8a18, 87604b18) that referenced
the now-removed ClaudeQuickToggles component.

The whitelist-based partial merge approach had critical issues:
- Non-whitelisted custom fields were lost during provider switching
- Backfill permanently stripped non-key fields from the database
- Whitelist required constant maintenance to track upstream changes

This restores the proven "full config overwrite + Common Config Snippet"
architecture where each provider stores its complete configuration and
shared settings are managed via a separate snippet mechanism.

Reverted commits:
- 24fa8a18: context-aware JSON editor hint + hide quick toggles
- 87604b18: hide ClaudeQuickToggles when creating
- 992dda5c: partial key-field merging refactoring

Restored:
- Full config snapshot write (write_live_snapshot) for Claude/Codex/Gemini
- Full config backfill (settings_config = live_config)
- Common Config Snippet UI and backend commands
- 6 frontend components/hooks for common config editing
- configApi barrel export and DB snippet methods

Removed:
- ClaudeQuickToggles component
- write_live_partial / backfill_key_fields / patch_claude_live
- All KEY_FIELDS constants

src/config/claudeProviderPresets.ts

@@ -316,10 +316,12 @@ export const providerPresets: ProviderPreset[] = [
     name: "AiHubMix",
     websiteUrl: "https://aihubmix.com",
     apiKeyUrl: "https://aihubmix.com",
+    // 说明：该供应商使用 ANTHROPIC_API_KEY（而非 ANTHROPIC_AUTH_TOKEN）
+    apiKeyField: "ANTHROPIC_API_KEY",
     settingsConfig: {
       env: {
         ANTHROPIC_BASE_URL: "https://aihubmix.com",
-        ANTHROPIC_AUTH_TOKEN: "",
+        ANTHROPIC_API_KEY: "",
       },
     },
     // 请求地址候选（用于地址管理/测速），用户可自行选择/覆盖