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/init_status.rs

@@ -52,6 +52,47 @@ pub fn take_migration_success() -> bool {
     }
 }
 
+// ============================================================
+// Skills SSOT 迁移结果状态
+// ============================================================
+
+#[derive(Debug, Clone, Serialize)]
+pub struct SkillsMigrationPayload {
+    pub count: usize,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub error: Option<String>,
+}
+
+static SKILLS_MIGRATION_RESULT: OnceLock<RwLock<Option<SkillsMigrationPayload>>> = OnceLock::new();
+
+fn skills_migration_cell() -> &'static RwLock<Option<SkillsMigrationPayload>> {
+    SKILLS_MIGRATION_RESULT.get_or_init(|| RwLock::new(None))
+}
+
+pub fn set_skills_migration_result(count: usize) {
+    if let Ok(mut guard) = skills_migration_cell().write() {
+        *guard = Some(SkillsMigrationPayload { count, error: None });
+    }
+}
+
+pub fn set_skills_migration_error(error: String) {
+    if let Ok(mut guard) = skills_migration_cell().write() {
+        *guard = Some(SkillsMigrationPayload {
+            count: 0,
+            error: Some(error),
+        });
+    }
+}
+
+/// 获取并消费 Skills 迁移结果（只返回一次 Some，之后返回 None）
+pub fn take_skills_migration_result() -> Option<SkillsMigrationPayload> {
+    if let Ok(mut guard) = skills_migration_cell().write() {
+        guard.take()
+    } else {
+        None
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;