Kiosk start, offline and setup pages in the InfoFlow display style

Dark grey background, name top left, date and clock top right, a flat
panel with a blue top edge. The pages show the kiosk link (token masked)
and the management address; the clock code is shared in kiosk.js.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/voxip_kiosk/config.py

@@ -123,6 +123,12 @@ class ConfigError(Exception):
         self.errors = errors
 
 
+def admin_url(config: dict[str, Any], hostname: str) -> str:
+    """Address of the web interface as shown on the kiosk screen."""
+    scheme = "https" if config["admin_https"] else "http"
+    return f"{scheme}://{hostname}.local:{config['admin_port']}"
+
+
 def validate(updates: dict[str, Any]) -> dict[str, Any]:
     """Validate known keys in ``updates``; raise ConfigError listing every problem."""
     clean: dict[str, Any] = {}