Add top nav bar and Heimservice page

Adds a Bestellübersicht/Heimservice/Abmelden nav bar to the layout, and
builds out the Heimservice page with a per-restaurant control panel
(availability windows, ORDER WebApp link, password reset, mobile-number
editor, and a consolidated call popup) mirroring the old interface's
button layout in the current design system.

src/lib/types.ts

@@ -36,7 +36,10 @@ export type Restaurant = {
   phone1: string;
   phone2?: string;
   mobile?: string;
+  mobile2?: string;
   orderUrl: string;
+  /** Zeitfenster für den Heimservice, z. B. Mittags- und Abendschicht. Zweites Fenster optional. */
+  heimserviceWindows: [string, string | undefined];
 };
 
 export type Customer = {