feat: add Demo Requests module

- New demo_requests table (SQLAlchemy model + Alembic-ready)
- Public POST /api/demo-requests endpoint for the TapTrack website form
- Super-admin GET/PUT/DELETE endpoints to manage leads
- DemoRequestsPage.vue with stats row, filterable table, status updates, notes modal
- Sidebar nav item and route registered

backend/app/main.py

@@ -5,11 +5,12 @@ from fastapi.middleware.cors import CORSMiddleware
 
 from app.database import engine, Base
 # Import all models so Alembic/SQLAlchemy picks them up
-from app.models import user, school, license, sms, billing, ticket, audit, announcement, email_log, report  # noqa
+from app.models import user, school, license, sms, billing, ticket, audit, announcement, email_log, report, demo_request  # noqa
 
 from app.routers import auth, schools, licenses, sms as sms_router, billing as billing_router
 from app.routers import tickets, users, dashboard, school_portal, announcements, sync, email as email_router
 from app.routers import search, audit
+from app.routers import demo_requests as demo_requests_router
 
 @asynccontextmanager
 async def lifespan(app: FastAPI):
@@ -48,6 +49,7 @@ app.include_router(sync.router)
 app.include_router(email_router.router)
 app.include_router(search.router)
 app.include_router(audit.router)
+app.include_router(demo_requests_router.router)
 
 @app.get("/api/health")
 async def health():