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

frontend/src/components/ui/card.tsx

@@ -3,7 +3,7 @@ import { cn } from '@/lib/utils'
 
 const Card = React.forwardRef<HTMLDivElement, React.HTMLAttributes<HTMLDivElement>>(
   ({ className, ...props }, ref) => (
-    <div ref={ref} className={cn('rounded-xl border border-gray-200 bg-white text-gray-900 shadow-sm dark:border-gray-700 dark:bg-gray-800 dark:text-gray-100', className)} {...props} />
+    <div ref={ref} className={cn('rounded-xl border border-border bg-card text-foreground shadow-sm', className)} {...props} />
   ),
 )
 Card.displayName = 'Card'
@@ -24,7 +24,7 @@ CardTitle.displayName = 'CardTitle'
 
 const CardDescription = React.forwardRef<HTMLParagraphElement, React.HTMLAttributes<HTMLParagraphElement>>(
   ({ className, ...props }, ref) => (
-    <p ref={ref} className={cn('text-sm text-gray-500 dark:text-gray-400', className)} {...props} />
+    <p ref={ref} className={cn('text-sm text-muted-foreground', className)} {...props} />
   ),
 )
 CardDescription.displayName = 'CardDescription'