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>

tsconfig.app.json

@@ -7,5 +7,5 @@
 		"types": ["node"]
 	},
 	"include": ["src/**/*.ts"],
-	"exclude": ["src/**/*.spec.ts"]
+	"exclude": ["src/**/*.spec.ts", "src/server.ts"]
 }