docs & cleanup: update stack info, remove dead code, fix backend bugs

- Fix AGENTS.md and 技术架构设计.md to reflect actual stack (Prisma+MySQL, static export, PM2)
- Remove 4 unused frontend components (page-transition, page-layout, image-upload, section-card)
- Fix card.tsx hardcoded colors → CSS variables
- Remove provider name from model selector, remove sensenova-u1-fast from models
- Fix analytics.controller.ts raw SQL table names (runtime bug)
- Add JWT auth guard to tools POST endpoint
- Fix AI gateway test: update env vars and model names
- Fix admin test: mock role structure for Prisma relation

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

@@ -138,7 +138,7 @@ export class AnalyticsController {
     if (type === 'users') {
       const data = await this.prisma.$queryRaw<{ date: string; count: bigint }[]>`
         SELECT DATE(created_at) as date, COUNT(*) as count 
-        FROM User 
+        FROM users 
         WHERE deleted_at IS NULL AND created_at >= ${startDate}
         GROUP BY DATE(created_at)
         ORDER BY date
@@ -149,7 +149,7 @@ export class AnalyticsController {
     if (type === 'orders') {
       const data = await this.prisma.$queryRaw<{ date: string; count: bigint; revenue: bigint }[]>`
         SELECT DATE(created_at) as date, COUNT(*) as count, COALESCE(SUM(amount), 0) as revenue
-        FROM \`Order\` 
+        FROM orders 
         WHERE status = 'PAID' AND created_at >= ${startDate}
         GROUP BY DATE(created_at)
         ORDER BY date
@@ -160,7 +160,7 @@ export class AnalyticsController {
     if (type === 'sessions') {
       const data = await this.prisma.$queryRaw<{ date: string; count: bigint }[]>`
         SELECT DATE(created_at) as date, COUNT(*) as count 
-        FROM sandbox_session 
+        FROM sandbox_sessions 
         WHERE created_at >= ${startDate}
         GROUP BY DATE(created_at)
         ORDER BY date

backend/src/modules/admin/tests/admin.service.spec.ts

@@ -51,7 +51,7 @@ describe('AdminService', () => {
       id: 1,
       username: 'admin',
       passwordHash: '$2a$10$hashed',
-      role: 'superadmin',
+      role: { name: 'superadmin' },
       status: 'ACTIVE',
     };