feat(server): serve the client-only build with Bun

Angular's server build needs Node loader hooks that Bun does not apply,
and every route is client-rendered, so Angular now builds a client-only
bundle and a small Bun.serve server delivers it: hashed assets with the
one-year cache, index.html revalidated, extension-less routes falling
back to index.html, missing assets 404, traversal and malformed paths
rejected, and other methods 405. Express, @angular/ssr and the unused
hydration provider are removed. Both Docker stages use the pinned
oven/bun:1.4.3-alpine image without Node, and the health checks use
Bun's fetch.

Refs #292

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/app/app.config.ts

@@ -6,13 +6,11 @@ import {
 import { provideRouter } from '@angular/router';
 
 import { routes } from './app.routes';
-import { provideClientHydration, withEventReplay } from '@angular/platform-browser';
 
 export const appConfig: ApplicationConfig = {
 	providers: [
 		provideBrowserGlobalErrorListeners(),
 		provideZonelessChangeDetection(),
 		provideRouter(routes),
-		provideClientHydration(withEventReplay()),
 	],
 };