feat(12-03): connection-ID routing, rename, session folder memory, thin views

- Route /cloud/:connectionId/:folderId replaces /cloud/:provider/:folderId
- api/cloud.js: getCloudFoldersByConnectionId + renameCloudConnection
- cloudConnections store: rename, selectConnection, setBrowseState, defaultDisplayName, session storage helpers
- CloudStorageView: thin — passes connectionRoots to StorageBrowser
- CloudFolderView: thin — uses connectionId param, never provider slug
- SettingsCloudTab: inline rename input for each active connection
- 27 tests pass: store, view, settings

frontend/src/router/index.js

@@ -62,7 +62,7 @@ const routes = [
     meta: { requiresAuth: true },
   },
   {
-    path: '/cloud/:provider/:folderId(.*)',
+    path: '/cloud/:connectionId/:folderId(.*)',
     name: 'cloud-folder',
     component: () => import('../views/CloudFolderView.vue'),
     meta: { requiresAuth: true },