fix(@angular/build): pass an explicit port of 0 through to the dev server

Previously, requesting an ephemeral port (`--port 0`) was resolved by
binding a throwaway net.Server to learn the real port before handing
that concrete number to Vite or webpack-dev-server, which then bound
it again. This avoided a Vite bug where `server.port: 0` was ignored
and the default port (5173) was used instead.

That bug is fixed upstream (vitejs/vite#7529, vitejs/vite#23158), and
webpack-dev-server has always bound port 0 correctly via Node's own
http.Server. Pass 0 straight through instead of pre-resolving it,
removing the redundant double-bind.

Verified via the existing port_spec.ts "random free port" test for
both the Vite-based and webpack-based dev server, which covers this
exact scenario.

(cherry picked from commit 3123cf2)

Author: MeAkib

packages/angular/build/src/utils/check-port.ts

@@ -15,11 +15,11 @@ function createInUseError(port: number): Error {
 }
 
 export async function checkPort(port: number, host: string): Promise<number> {
-  // Disabled due to Vite not handling port 0 and instead always using the default value (5173)
-  // TODO: Enable this again once Vite is fixed
-  // if (port === 0) {
-  //   return 0;
-  // }
+  // A port of 0 requests an OS-assigned ephemeral port. Vite now binds this correctly
+  // (https://github.com/vitejs/vite/pull/23158); webpack-dev-server always has.
+  if (port === 0) {
+    return 0;
+  }
 
   return new Promise<number>((resolve, reject) => {
     const server = createServer();