feat(config): add system configuration module (Phase 3)

Implement the complete erp-config crate with:
- Data dictionaries (CRUD + items management)
- Dynamic menus (tree structure with role filtering)
- System settings (hierarchical: platform > tenant > org > user)
- Numbering rules (concurrency-safe via PostgreSQL advisory_lock)
- Theme and language configuration (via settings store)
- 6 database migrations (dictionaries, menus, settings, numbering_rules)
- Frontend Settings page with 5 tabs (dictionary, menu, numbering, settings, theme)

Refactor: move RBAC functions (require_permission) from erp-auth to erp-core
to avoid cross-module dependencies.

Add 20 new seed permissions for config module operations.

apps/web/src/App.tsx

@@ -8,6 +8,7 @@ import Home from './pages/Home';
 import Roles from './pages/Roles';
 import Users from './pages/Users';
 import Organizations from './pages/Organizations';
+import Settings from './pages/Settings';
 import { useAuthStore } from './stores/auth';
 import { useAppStore } from './stores/app';
 
@@ -45,7 +46,7 @@ export default function App() {
                     <Route path="/users" element={<Users />} />
                     <Route path="/roles" element={<Roles />} />
                     <Route path="/organizations" element={<Organizations />} />
-                    <Route path="/settings" element={<div>系统设置（开发中）</div>} />
+                    <Route path="/settings" element={<Settings />} />
                   </Routes>
                 </MainLayout>
               </PrivateRoute>