feat: REST API + operator admin route

views_api.py exposes the booking flow over HTTP — availability check,
guest booking request (check-then-hold with canonical amount_sat), room
publish, blocks. REST and Nostr are two doors into the same crud flow;
FX + invoice creation marked TODO. views.py serves the operator page.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019VUQCfdqiLSsFS2jcGnaFD

views.py

@@ -0,0 +1,22 @@
+"""Frontend routes — serves the operator admin page. SKETCH: single index
+template; the guest-facing booking UI is expected to live in the webapp
+(standalone app pattern), talking to this extension over Nostr/REST."""
+
+from fastapi import APIRouter, Depends, Request
+from fastapi.responses import HTMLResponse
+from lnbits.core.models import User
+from lnbits.decorators import check_user_exists
+from lnbits.helpers import template_renderer
+
+chatelet_generic_router = APIRouter()
+
+
+def chatelet_renderer():
+    return template_renderer(["chatelet/templates"])
+
+
+@chatelet_generic_router.get("/", response_class=HTMLResponse)
+async def index(request: Request, user: User = Depends(check_user_exists)):
+    return chatelet_renderer().TemplateResponse(
+        "chatelet/index.html", {"request": request, "user": user.json()}
+    )