Refactor topbar HTML, projects TS and styles

Minor markup and formatting cleanup plus layout adjustments.

- topbar.component.html: removed mat-toolbar color attribute, compacted/normalized element attributes and spacing, fixed small markup spacing issues.
- projects.component.ts: code formatting and whitespace normalization (imports, property spacing, object literals, small function signature/timeout formatting); no logic changes.
- styles.scss: reorganized topbar rules (added app-topbar wrapper, display and color), switched .hero from grid to flex with responsive flex-basis, adjusted photo and intro flex behavior, increased project grid column min width and centered grid with max-width, removed featured card full-width grid span.

These changes improve consistency, readability and adjust layout/responsiveness of the topbar/hero/project grid.

src/app/layout/topbar/topbar.component.html

@@ -1,11 +1,7 @@
-<mat-toolbar class="topbar" color="primary" (keydown)="onKeydown($event)">
+<mat-toolbar class="topbar" (keydown)="onKeydown($event)">
   <a class="brand" routerLink="/">
-    <img class="logo-dot"
-         src="{{AssetsConstants.LOGO}}"
-         alt="" aria-hidden="true"
-         draggable="false"
-         oncontextmenu="return false;"
-    >
+    <img class="logo-dot" src="{{AssetsConstants.LOGO}}" alt="" aria-hidden="true" draggable="false"
+      oncontextmenu="return false;">
     <span class="brand-text">{{ 'APP.TITLE' | translate }}</span>
   </a>
 
@@ -17,11 +13,7 @@
   </nav>
 
   <!-- Mobile nav menu button -->
-  <button
-    mat-icon-button
-    class="nav-menu-btn"
-    [matMenuTriggerFor]="navMenu"
-    aria-label="Open navigation">
+  <button mat-icon-button class="nav-menu-btn" [matMenuTriggerFor]="navMenu" aria-label="Open navigation">
     <mat-icon>menu</mat-icon>
   </button>
 
@@ -46,7 +38,8 @@
   <span class="spacer"></span>
 
   <!-- Settings: Sprache + Theme -->
-  <button mat-icon-button [matMenuTriggerFor]="settingsMenu" aria-label="Open settings" matTooltip="{{ 'TOPBAR.SETTINGS' | translate }}">
+  <button mat-icon-button [matMenuTriggerFor]="settingsMenu" aria-label="Open settings"
+    matTooltip="{{ 'TOPBAR.SETTINGS' | translate }}">
     <mat-icon>tune</mat-icon>
   </button>
 
@@ -58,7 +51,7 @@
         <span>{{ 'LANG.DE' | translate }}</span>
         @if (lang.lang() === 'de')
         {
-          <mat-icon >check</mat-icon>
+        <mat-icon>check</mat-icon>
         }
       </button>
       <button mat-menu-item (click)="setLang('en')">
@@ -66,7 +59,7 @@
         <span>{{ 'LANG.EN' | translate }}</span>
         @if (lang.lang() === 'en')
         {
-          <mat-icon>check</mat-icon>
+        <mat-icon>check</mat-icon>
         }
       </button>
     </div>
@@ -82,4 +75,4 @@
       </button>
     </div>
   </mat-menu>
-</mat-toolbar>
+</mat-toolbar>