refactor(header): modernize header styles and remove unused module

Update header component UI and streamline imports.

- Remove MatToolbarModule import and module list entry
  because the toolbar styling is handled by local SCSS and the
  Angular Material toolbar is no longer required.
- Rewrite header SCSS to introduce a .modern-header wrapper with
  consistent sizing, padding, alignment and a subtle bottom border.
- Add layered ambient and depth effects: refined ::before ambient
  gradient (headerAmbience), ::after bottom accent, and adjusted
  keyframes for a gentler motion.
- Refine home-header styles to target .modern-header and tune colors
  and gradients for a cohesive dark theme.
- Rework .brand-block visuals: lighter glass effect, adjusted
  radii, blur, borders, hover transform, and shadowing for a modern
  elevated look.
- Minor cleanup: remove legacy variables and comments; improve
  box-sizing, layout, and pointer-event handling to ensure expected
  interaction regions.

These changes modernize the header's visual design, improve layout
consistency across pages, and remove an unnecessary module import.

apps/web/src/app/shared/components/header/header.component.ts

@@ -6,7 +6,6 @@ import { MatDialog } from '@angular/material/dialog';
 import { MatDividerModule } from '@angular/material/divider';
 import { MatIconModule } from '@angular/material/icon';
 import { MatMenuModule } from '@angular/material/menu';
-import { MatToolbarModule } from '@angular/material/toolbar';
 import { MatTooltipModule } from '@angular/material/tooltip';
 import { ActivatedRoute, Router } from '@angular/router';
 import { Store } from '@ngrx/store';
@@ -32,7 +31,6 @@ import {
         MatDividerModule,
         MatIconModule,
         MatMenuModule,
-        MatToolbarModule,
         MatTooltipModule,
         ReactiveFormsModule,
         TranslateModule,