feat: inject ThemeService into App component and enhance responsive styles for navigation items

frontend/src/app/components/workspace-navigation/workspace-navigation.css

@@ -69,28 +69,6 @@
 	background: var(--surface-accent);
 }
 
-@media (max-width: 959px) {
-	.navigation-item .mdc-button__label {
-		display: flex;
-		width: 100%;
-		height: 100%;
-		min-width: 0;
-		flex-direction: column;
-		align-items: center;
-		justify-content: center;
-	}
-
-	.navigation-item span {
-		width: 100%;
-		min-width: 0;
-		overflow-wrap: break-word;
-		font-size: 0.62rem;
-		line-height: 1.05;
-		text-align: center;
-		white-space: normal;
-	}
-}
-
 @media (min-width: 960px) {
 	.app-navigation {
 		top: 0;
@@ -209,4 +187,4 @@
 		border-radius: 0;
 		font-size: 0.75rem;
 	}
-}
+}