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/commands/misc.rs

@@ -1,6 +1,6 @@
 #![allow(non_snake_case)]
 
-use crate::init_status::InitErrorPayload;
+use crate::init_status::{InitErrorPayload, SkillsMigrationPayload};
 use tauri::AppHandle;
 use tauri_plugin_opener::OpenerExt;
 
@@ -65,6 +65,13 @@ pub async fn get_migration_result() -> Result<bool, String> {
     Ok(crate::init_status::take_migration_success())
 }
 
+/// 获取 Skills 自动导入（SSOT）迁移结果（若有）。
+/// 只返回一次 Some({count})，之后返回 None，用于前端显示一次性 Toast 通知。
+#[tauri::command]
+pub async fn get_skills_migration_result() -> Result<Option<SkillsMigrationPayload>, String> {
+    Ok(crate::init_status::take_skills_migration_result())
+}
+
 #[derive(serde::Serialize)]
 pub struct ToolVersion {
     name: String,