feat(skills): add skill sync method setting (symlink/copy)

- Add SyncMethod enum (Auto/Symlink/Copy) in Rust backend
- Implement sync_to_app_dir with symlink support (cross-platform)
- Add SkillSyncMethodSettings UI component (simplified 2-button selector)
- Add i18n support for zh/en/ja
- Replace copy_to_app with configurable sync_to_app_dir
- Add skill_sync_method field to AppSettings

User can now choose between symlink (disk space saving) or copy (best compatibility) in Settings > General.

src/components/providers/forms/hooks/useModelState.ts

@@ -51,19 +51,19 @@ export function useModelState({
 }: UseModelStateProps) {
   // Initialize state by parsing config directly (fixes edit mode backfill)
   const [claudeModel, setClaudeModel] = useState(
-    () => parseModelsFromConfig(settingsConfig).model
+    () => parseModelsFromConfig(settingsConfig).model,
   );
   const [reasoningModel, setReasoningModel] = useState(
-    () => parseModelsFromConfig(settingsConfig).reasoning
+    () => parseModelsFromConfig(settingsConfig).reasoning,
   );
   const [defaultHaikuModel, setDefaultHaikuModel] = useState(
-    () => parseModelsFromConfig(settingsConfig).haiku
+    () => parseModelsFromConfig(settingsConfig).haiku,
   );
   const [defaultSonnetModel, setDefaultSonnetModel] = useState(
-    () => parseModelsFromConfig(settingsConfig).sonnet
+    () => parseModelsFromConfig(settingsConfig).sonnet,
   );
   const [defaultOpusModel, setDefaultOpusModel] = useState(
-    () => parseModelsFromConfig(settingsConfig).opus
+    () => parseModelsFromConfig(settingsConfig).opus,
   );
 
   const isUserEditingRef = useRef(false);