fix(saas): deep audit round industry template system - critical fixes

C1: Use backend createAgentFromTemplate API + tools forwarding
C3: seed source='builtin' instead of 'custom'
C4: immutable clone data handling (return fresh from store) + spread)
H3: assignTemplate error propagation (try/catch)
H4: input validation for name/fields
H5: assign_template account existence check
H6: remove dead route get_full_template
H7: model fallback gpt-4o-mini (hardcoded constant)
H8: logout clears template state
H9: console.warn -> structured logger
C2: restoreSession fetches assignedTemplate

desktop/src/store/saasStore.ts

@@ -397,8 +397,10 @@ export const useSaaSStore = create<SaaSStore>((set, get) => {
         authToken: null,
         connectionMode: 'tauri',
         availableModels: [],
+        availableTemplates: [],
+        assignedTemplate: null,
         error: null,
-        totpRequired: false,
+        toTopRequired: false,
         totpSetupData: null,
       });
     },
@@ -720,6 +722,8 @@ export const useSaaSStore = create<SaaSStore>((set, get) => {
         connectionMode: loadConnectionMode() === 'saas' ? 'saas' : 'tauri',
       });
       get().fetchAvailableModels().catch(() => {});
+      get().fetchAvailableTemplates().catch(() => {});
+      get().fetchAssignedTemplate().catch(() => {});
       get().syncConfigFromSaaS().then(() => {
         get().pushConfigToSaaS().catch(() => {});
       }).catch(() => {});