feat: add config directory override support for WSL

- Add persistent app settings with custom Claude Code and Codex config directories
- Add config directory override UI in settings modal with manual input, browse, and reset options
- Integrate tauri-plugin-dialog for native directory picker
- Support WSL and other special environments where config paths need manual specification

Changes:
- settings.rs: Implement settings load/save and directory override logic
- SettingsModal: Add config directory override UI components
- API: Add get_config_dir and pick_directory commands

src-tauri/capabilities/default.json

@@ -9,6 +9,7 @@
     "core:default",
     "opener:default",
     "updater:default",
-    "process:allow-restart"
+    "process:allow-restart",
+    "dialog:default"
   ]
 }