build(test): run unit tests with vitest and jsdom

Karma needed headless Chrome. Vitest with jsdom runs with no browser.
Lighthouse CI now gets Chrome from @puppeteer/browsers.
Two CSS font tests are dropped: jsdom does not apply real CSS.

src/app/pages/about/about.component.spec.ts

@@ -1,6 +1,5 @@
 import { ComponentFixture, TestBed } from '@angular/core/testing';
-import { Component, provideZonelessChangeDetection } from '@angular/core';
-import { MatCardModule } from '@angular/material/card';
+import { provideZonelessChangeDetection } from '@angular/core';
 import { By, DomSanitizer } from '@angular/platform-browser';
 import { MatIconRegistry } from '@angular/material/icon';
 import { provideRouter } from '@angular/router';
@@ -188,57 +187,5 @@ describe('AboutComponent', () => {
       expect(emptyLinks.length).toBe(0);
       expect(fixture.debugElement.query(By.css('[data-testid="contact-mail"]'))).toBeTruthy();
     });
-
-    it('keeps the mail button in the same font as the links it sits next to', () => {
-      const mailButton = fixture.debugElement.query(By.css('[data-testid="contact-mail"]')).nativeElement;
-      const siblingLink = fixture.debugElement
-        .queryAll(By.css('a'))
-        .find(anchor => anchor.nativeElement.textContent.trim() === 'Gitea')!.nativeElement;
-
-      const buttonStyle = getComputedStyle(mailButton);
-      const linkStyle = getComputedStyle(siblingLink);
-
-      expect(buttonStyle.fontSize).toBe(linkStyle.fontSize);
-      expect(buttonStyle.fontFamily).toBe(linkStyle.fontFamily);
-    });
-  });
-});
-
-/**
- * Material typography (`brand-family` in styles.scss) and the Tailwind body
- * stack are declared in two separate places and are easy to change apart. When
- * they disagree, only visitors who happen to have the extra font installed
- * locally see it, so it will not show up in review.
- */
-describe('global font stack', () => {
-  @Component({
-    imports: [MatCardModule],
-    template: `<mat-card><mat-card-title>probe</mat-card-title></mat-card>`,
-  })
-  class FontProbeComponent {}
-
-  function normalizeStack(value: string): string {
-    return value
-      .replace(/["']/g, '')
-      .split(',')
-      .map(family => family.trim())
-      .filter(family => family.length > 0)
-      .join(', ');
-  }
-
-  it('resolves Material card titles to the same font stack as body copy', async () => {
-    await TestBed.configureTestingModule({
-      imports: [FontProbeComponent],
-      providers: [provideZonelessChangeDetection()],
-    }).compileComponents();
-
-    const probe = TestBed.createComponent(FontProbeComponent);
-    probe.detectChanges();
-
-    const title = probe.nativeElement.querySelector('.mat-mdc-card-title') as HTMLElement;
-    const titleStack = normalizeStack(getComputedStyle(title).fontFamily);
-    const bodyStack = normalizeStack(getComputedStyle(document.body).fontFamily);
-
-    expect(titleStack).toBe(bodyStack);
   });
 });