style: Keyfarbe #051e23 + Pfandlogo einbauen

- Tailwind brand-Palette neu verankert: #051e23 = brand-900 (Keyfarbe),
  brand-50..950 als dunkles Teal-Spektrum (warm)
- btn-primary: bg-brand-900 hover:bg-brand-800 (statt indigo)
- input/badge: focus/text auf brand-700/900
- public/pfandlogo.jpg eingebaut als:
  - Favicon + Apple-Touch-Icon
  - Login (zentral, statt P-Box)
  - TopNav-Header (statt P-Box)
  - SuperAdmin-Header (statt P-Box)
- index.html theme-color #051e23
- manifest.json theme_color #051e23 + Logo als zusaetzliches Icon

public/manifest.json

@@ -4,9 +4,10 @@
   "start_url": ".",
   "display": "standalone",
   "background_color": "#f8fafc",
-  "theme_color": "#4338ca",
+  "theme_color": "#051e23",
   "description": "Digitale Pfand- und Tourenverwaltung",
   "icons": [
+    { "src": "pfandlogo.jpg", "sizes": "1000x1000", "type": "image/jpeg" },
     { "src": "icon-192.png", "sizes": "192x192", "type": "image/png" },
     { "src": "icon-512.png", "sizes": "512x512", "type": "image/png" }
   ]