feat(app): add prerender, self-hosted fonts and privacy page

Fonts come from npm, not Google, so no third-party font requests.
Pages are prerendered at build time; browser-only code is guarded.
nginx serves per-route HTML, a real 404 and gzip.

src/app/pages/about/about.component.html

@@ -24,10 +24,7 @@
           </div>
           <div class="flex items-center flex-wrap gap-[0.4rem]">
             <mat-icon aria-hidden="true">email</mat-icon>
-            <button type="button" class="link-button" data-testid="contact-mail"
-              (click)="SharedFunctions.openMail($event)">
-              {{ 'ABOUT.CONTACT_ME' | translate }}
-            </button>
+            <a href="mailto:info@andreas-dahm.eu" data-testid="contact-mail">info&#64;andreas-dahm.eu</a>
           </div>
           <div class="flex items-center flex-wrap gap-[0.4rem]">
             <mat-icon aria-hidden="true">data_object</mat-icon>