feat: add skill storage location toggle between CC Switch and ~/.agents/skills

Allow users to choose between storing skills in CC Switch's managed
directory (~/.cc-switch/skills/) or the Agent Skills open standard
directory (~/.agents/skills/). Includes migration logic that safely
moves files before updating settings, with confirmation dialog for
non-empty installations.

src-tauri/src/settings.rs

@@ -6,7 +6,7 @@ use std::sync::{OnceLock, RwLock};
 
 use crate::app_config::AppType;
 use crate::error::AppError;
-use crate::services::skill::SyncMethod;
+use crate::services::skill::{SkillStorageLocation, SyncMethod};
 
 /// 自定义端点配置（历史兼容，实际存储在 provider.meta.custom_endpoints）
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -245,6 +245,9 @@ pub struct AppSettings {
     /// Skill 同步方式：auto（默认，优先 symlink）、symlink、copy
     #[serde(default)]
     pub skill_sync_method: SyncMethod,
+    /// Skill 存储位置：cc_switch（默认）或 unified（~/.agents/skills/）
+    #[serde(default)]
+    pub skill_storage_location: SkillStorageLocation,
 
     // ===== WebDAV 同步设置 =====
     #[serde(default, skip_serializing_if = "Option::is_none")]
@@ -307,6 +310,7 @@ impl Default for AppSettings {
             current_provider_opencode: None,
             current_provider_openclaw: None,
             skill_sync_method: SyncMethod::default(),
+            skill_storage_location: SkillStorageLocation::default(),
             webdav_sync: None,
             webdav_backup: None,
             backup_interval_hours: None,
@@ -642,6 +646,26 @@ pub fn get_skill_sync_method() -> SyncMethod {
         .skill_sync_method
 }
 
+// ===== Skill 存储位置管理函数 =====
+
+/// 获取 Skill 存储位置配置
+pub fn get_skill_storage_location() -> SkillStorageLocation {
+    settings_store()
+        .read()
+        .unwrap_or_else(|e| {
+            log::warn!("设置锁已毒化，使用恢复值: {e}");
+            e.into_inner()
+        })
+        .skill_storage_location
+}
+
+/// 设置 Skill 存储位置
+pub fn set_skill_storage_location(location: SkillStorageLocation) -> Result<(), AppError> {
+    mutate_settings(|s| {
+        s.skill_storage_location = location;
+    })
+}
+
 // ===== 备份策略管理函数 =====
 
 /// Get the effective auto-backup interval in hours (default 24)