feat(skills): unified management architecture with SSOT and React Query

- Introduce SSOT (Single Source of Truth) at ~/.cc-switch/skills/
- Add three-app toggle support (Claude/Codex/Gemini) for each skill
- Refactor frontend to use TanStack Query hooks instead of manual state
- Add UnifiedSkillsPanel for managing installed skills with app toggles
- Add useSkills.ts with declarative data fetching hooks
- Extend skills.ts API with unified install/uninstall/toggle methods
- Support importing unmanaged skills from app directories
- Add v2→v3 database migration for new skills table structure

src-tauri/src/app_config.rs

@@ -55,6 +55,110 @@ impl McpApps {
     }
 }
 
+/// Skill 应用启用状态（标记 Skill 应用到哪些客户端）
+#[derive(Debug, Clone, Serialize, Deserialize, Default, PartialEq)]
+pub struct SkillApps {
+    #[serde(default)]
+    pub claude: bool,
+    #[serde(default)]
+    pub codex: bool,
+    #[serde(default)]
+    pub gemini: bool,
+}
+
+impl SkillApps {
+    /// 检查指定应用是否启用
+    pub fn is_enabled_for(&self, app: &AppType) -> bool {
+        match app {
+            AppType::Claude => self.claude,
+            AppType::Codex => self.codex,
+            AppType::Gemini => self.gemini,
+        }
+    }
+
+    /// 设置指定应用的启用状态
+    pub fn set_enabled_for(&mut self, app: &AppType, enabled: bool) {
+        match app {
+            AppType::Claude => self.claude = enabled,
+            AppType::Codex => self.codex = enabled,
+            AppType::Gemini => self.gemini = enabled,
+        }
+    }
+
+    /// 获取所有启用的应用列表
+    pub fn enabled_apps(&self) -> Vec<AppType> {
+        let mut apps = Vec::new();
+        if self.claude {
+            apps.push(AppType::Claude);
+        }
+        if self.codex {
+            apps.push(AppType::Codex);
+        }
+        if self.gemini {
+            apps.push(AppType::Gemini);
+        }
+        apps
+    }
+
+    /// 检查是否所有应用都未启用
+    pub fn is_empty(&self) -> bool {
+        !self.claude && !self.codex && !self.gemini
+    }
+
+    /// 仅启用指定应用（其他应用设为禁用）
+    pub fn only(app: &AppType) -> Self {
+        let mut apps = Self::default();
+        apps.set_enabled_for(app, true);
+        apps
+    }
+}
+
+/// 已安装的 Skill（v3.10.0+ 统一结构）
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct InstalledSkill {
+    /// 唯一标识符（格式："owner/repo:directory" 或 "local:directory"）
+    pub id: String,
+    /// 显示名称
+    pub name: String,
+    /// 描述
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub description: Option<String>,
+    /// 安装目录名（在 SSOT 目录中的子目录名）
+    pub directory: String,
+    /// 仓库所有者（GitHub 用户/组织）
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub repo_owner: Option<String>,
+    /// 仓库名称
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub repo_name: Option<String>,
+    /// 仓库分支
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub repo_branch: Option<String>,
+    /// README URL
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub readme_url: Option<String>,
+    /// 应用启用状态
+    pub apps: SkillApps,
+    /// 安装时间（Unix 时间戳）
+    pub installed_at: i64,
+}
+
+/// 未管理的 Skill（在应用目录中发现但未被 CC Switch 管理）
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct UnmanagedSkill {
+    /// 目录名
+    pub directory: String,
+    /// 显示名称（从 SKILL.md 解析）
+    pub name: String,
+    /// 描述
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub description: Option<String>,
+    /// 在哪些应用目录中发现（如 ["claude", "codex"]）
+    pub found_in: Vec<String>,
+}
+
 /// MCP 服务器定义（v3.7.0 统一结构）
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct McpServer {