feat(phase-11): add store coordinator layer

- Create store/index.ts as unified entry point
- Add useCompositeStore() hook for multi-slice access
- Add initializeStores() for client injection
- Re-export all individual stores for direct access
- Maintain backward compatibility with useGatewayStore

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/SYSTEM_ANALYSIS.md

@@ -567,12 +567,12 @@ ZCLAW 是基于 **OpenFang** (Rust Agent OS) 的 AI Agent 桌面客户端，核
     * ✅ `handStore.ts` (498 行) - Hands、Triggers、Approvals
     * ✅ `workflowStore.ts` (255 行) - Workflows、WorkflowRuns
     * ✅ `configStore.ts` (537 行) - QuickConfig、Channels、Skills、Models
+  * ✅ `store/index.ts` - 协调层，组合所有 stores
   * Store 行数: gatewayStore 1660 → 5 个子 Store (平均 358 行)
   * 待完成:
-    * 🔄 创建协调层 (coordinator)
-    * 🔄 更新组件导入
+    * 🔄 更新组件导入 (可选，向后兼容)
   * 代码质量:
     * ✅ TypeScript 类型检查通过
 
-*下一步: Phase 11 协调层创建*
+*下一步: Phase 12 性能优化*