Add new routes and improve theme and header responsiveness

Added routes for 'community', 'nicknames', and 'nickgenerator'. Enhanced theme switch positioning and responsive design for smaller screens. Moved header login button to a more consistent position and upgraded Angular Material to version 19.2.19 for better compatibility.

frontend/package.json

@@ -18,7 +18,7 @@
     "@angular/compiler": "^19.2.0",
     "@angular/core": "^19.2.0",
     "@angular/forms": "^19.2.0",
-    "@angular/material": "^19.2.18",
+    "@angular/material": "^19.2.19",
     "@angular/platform-browser": "^19.2.0",
     "@angular/platform-browser-dynamic": "^19.2.0",
     "@angular/router": "^19.2.0",