feat(saas): industry agent template assignment system

Phase 1-8 of industry-agent-delivery plan:

- DB migration: accounts.assigned_template_id (ON DELETE SET NULL)
- SaaS API: 4 new endpoints (assign/get/unassign/create-agent)
- Service layer: assign_template_to_account, get_assigned_template, unassign_template, create_agent_from_template)
- Types: AssignTemplateRequest, AgentConfigFromTemplate (capabilities merged into tools)
- Frontend SaaS Client: assignTemplate, getAssignedTemplate, unassignTemplate, createAgentFromTemplate
- saasStore: assignedTemplate state + login auto-fetch + actions
- saas-relay-client: fix unused import and saasUrl reference error
- connectionStore: fix relayModel undefined error
- capabilities default to glm-4-flash

- Route registration: new template assignment routes

Cospec and handlers consolidated

Build: cargo check --workspace PASS, tsc --noEmit Pass

desktop/src/lib/saas-client.ts

@@ -66,6 +66,7 @@ export type {
   CreateTemplateRequest,
   AgentTemplateAvailable,
   AgentTemplateFull,
+  AgentConfigFromTemplate,
 } from './saas-types';
 
 export { SaaSApiError } from './saas-errors';
@@ -101,6 +102,7 @@ import type {
   PaginatedResponse,
   AgentTemplateAvailable,
   AgentTemplateFull,
+  AgentConfigFromTemplate,
 } from './saas-types';
 import { SaaSApiError } from './saas-errors';
 import { clearSaaSSession } from './saas-session';
@@ -403,6 +405,41 @@ export class SaaSClient {
   async fetchTemplateFull(id: string): Promise<AgentTemplateFull> {
     return this.request<AgentTemplateFull>('GET', `/api/v1/agent-templates/${id}/full`);
   }
+
+  // --- Template Assignment ---
+
+  /**
+   * Assign a template to the current account.
+   * Records the user's industry choice for onboarding flow control.
+   */
+  async assignTemplate(templateId: string): Promise<AgentTemplateFull> {
+    return this.request<AgentTemplateFull>('POST', '/api/v1/accounts/me/assign-template', {
+      template_id: templateId,
+    });
+  }
+
+  /**
+   * Get the template currently assigned to the account.
+   * Returns null if no template is assigned.
+   */
+  async getAssignedTemplate(): Promise<AgentTemplateFull | null> {
+    return this.request<AgentTemplateFull | null>('GET', '/api/v1/accounts/me/assigned-template');
+  }
+
+  /**
+   * Unassign the current template from the account.
+   */
+  async unassignTemplate(): Promise<void> {
+    await this.request<unknown>('DELETE', '/api/v1/accounts/me/assigned-template');
+  }
+
+  /**
+   * Create an agent configuration from a template.
+   * Merges capabilities into tools, applies default model fallback.
+   */
+  async createAgentFromTemplate(templateId: string): Promise<AgentConfigFromTemplate> {
+    return this.request<AgentConfigFromTemplate>('POST', `/api/v1/agent-templates/${templateId}/create-agent`);
+  }
 }
 
 // === Install mixin methods ===