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/model-selector.tsx

@@ -52,7 +52,7 @@ export function ModelSelector({ value, onChange, className = '' }: ModelSelector
                 <span className={`w-2 h-2 rounded-full shrink-0 ${m.id === value ? 'bg-brand-600' : 'bg-muted-foreground/30'}`} />
                 <div className="flex-1 min-w-0">
                   <div className="text-sm font-medium text-foreground">{m.label}</div>
-                  <div className="text-xs text-muted-foreground">{m.provider} · {m.desc}</div>
+                  <div className="text-xs text-muted-foreground">{m.desc}</div>
                 </div>
                 {m.id === value && (
                   <svg className="w-4 h-4 text-brand-600 shrink-0" fill="none" stroke="currentColor" viewBox="0 0 24 24">