feat: add admin ideas management page with private notes

Adds a dedicated super admin page for managing idea submissions across
all tenants. Includes status summary cards, filterable/searchable table,
detail modal with status updates, and private admin notes for internal
tracking (sprint refs, thoughts, follow-ups). Notes are not visible to
tenant users.

- Database: admin_note column on shared.ideas (019 migration)
- Backend: PUT /admin/ideas/:id/note endpoint
- Frontend: AdminIdeasPage with table, filters, detail modal
- Sidebar: "Idea Submissions" nav link in admin sections
- Routing: /admin/ideas route under SuperAdminRoute guard

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

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

@@ -218,6 +218,17 @@ export class AdminController {
     return { success: true, idea };
   }
 
+  @Put('ideas/:id/note')
+  async updateIdeaNote(
+    @Req() req: any,
+    @Param('id') id: string,
+    @Body() body: { adminNote: string },
+  ) {
+    await this.requireSuperadmin(req);
+    const idea = await this.ideasService.updateNote(id, body.adminNote);
+    return { success: true, idea };
+  }
+
   @Put('organizations/:id/settings')
   async updateOrgSettings(
     @Req() req: any,

backend/src/modules/ideas/entities/idea.entity.ts

@@ -30,6 +30,9 @@ export class Idea {
   @Column({ length: 20, default: 'new' })
   status: string;
 
+  @Column({ name: 'admin_note', type: 'text', nullable: true })
+  adminNote: string;
+
   @CreateDateColumn({ name: 'created_at', type: 'timestamptz' })
   createdAt: Date;
 

backend/src/modules/ideas/ideas.service.ts

@@ -50,6 +50,7 @@ export class IdeasService {
         'idea.description AS description',
         'idea.status AS status',
         'idea.createdAt AS "createdAt"',
+        'idea.adminNote AS "adminNote"',
         'org.id AS "orgId"',
         'org.name AS "orgName"',
         'user.id AS "userId"',
@@ -75,4 +76,14 @@ export class IdeasService {
     idea.status = status;
     return this.ideasRepository.save(idea);
   }
+
+  async updateNote(id: string, adminNote: string): Promise<Idea> {
+    const idea = await this.ideasRepository.findOne({ where: { id } });
+    if (!idea) {
+      throw new NotFoundException('Idea not found');
+    }
+
+    idea.adminNote = adminNote;
+    return this.ideasRepository.save(idea);
+  }
 }