feat: add ideation feature with per-tenant toggle

Adds idea submission capability gated by a per-tenant feature flag.
Super admins can enable/disable ideation for specific tenants via the
admin tenant detail drawer. Users see a lightbulb icon in the header
when enabled, opening a modal to submit ideas (title + description).
Ideas are stored in shared schema for cross-tenant backlog querying.

- Database: shared.ideas table (018-ideas.sql migration)
- Backend: Ideas NestJS module (entity, service, controller)
- Admin API: GET /admin/ideas, PUT /admin/ideas/:id/status,
  PUT /admin/organizations/:id/settings
- Frontend: IdeaModal component, lightbulb ActionIcon in header
- Admin UI: Feature Toggles card with ideation Switch in drawer

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

backend/src/modules/auth/admin.controller.ts

@@ -5,6 +5,7 @@ import { AuthService } from './auth.service';
 import { UsersService } from '../users/users.service';
 import { OrganizationsService } from '../organizations/organizations.service';
 import { AdminAnalyticsService } from './admin-analytics.service';
+import { IdeasService } from '../ideas/ideas.service';
 import * as bcrypt from 'bcryptjs';
 
 @ApiTags('admin')
@@ -17,6 +18,7 @@ export class AdminController {
     private usersService: UsersService,
     private orgService: OrganizationsService,
     private analyticsService: AdminAnalyticsService,
+    private ideasService: IdeasService,
   ) {}
 
   private async requireSuperadmin(req: any) {
@@ -196,4 +198,34 @@ export class AdminController {
 
     return { success: true, organization: org };
   }
+
+  // ── Ideation ──
+
+  @Get('ideas')
+  async listAllIdeas(@Req() req: any) {
+    await this.requireSuperadmin(req);
+    return this.ideasService.findAll();
+  }
+
+  @Put('ideas/:id/status')
+  async updateIdeaStatus(
+    @Req() req: any,
+    @Param('id') id: string,
+    @Body() body: { status: string },
+  ) {
+    await this.requireSuperadmin(req);
+    const idea = await this.ideasService.updateStatus(id, body.status);
+    return { success: true, idea };
+  }
+
+  @Put('organizations/:id/settings')
+  async updateOrgSettings(
+    @Req() req: any,
+    @Param('id') id: string,
+    @Body() body: Record<string, any>,
+  ) {
+    await this.requireSuperadmin(req);
+    const org = await this.orgService.updateSettings(id, body);
+    return { success: true, organization: org };
+  }
 }