fix(@angular/build): only use external packages for polyfills when no local files are present

The polyfills bundle now conditionally employs external package resolution
only if no local files are detected in the polyfills array. If local files
are present, all polyfills are bundled together to ensure the import
execution order is correctly preserved between local and package-based
entries.

Author: clydin

packages/angular/build/src/tools/esbuild/application-code-bundle.ts

@@ -654,18 +654,19 @@ function getEsBuildCommonPolyfillsOptions(
   tryToResolvePolyfillsAsRelative: boolean,
   loadResultCache: LoadResultCache | undefined,
 ): BuildOptions | undefined {
-  const { jit, workspaceRoot, i18nOptions } = options;
+  const { jit, workspaceRoot, i18nOptions, externalPackages } = options;
+
+  let polyfills = options.polyfills ? [...options.polyfills] : [];
 
   const buildOptions = getEsBuildCommonOptions({
     ...options,
-    externalPackages: false,
+    // If any polyfills are local files, disable external packages for the polyfills build.
+    // This ensures that local files are properly bundled.
+    externalPackages: polyfills.some(isLocalFile) ? false : externalPackages,
   });
-  buildOptions.packages = 'bundle';
   buildOptions.splitting = false;
   buildOptions.plugins ??= [];
 
-  let polyfills = options.polyfills ? [...options.polyfills] : [];
-
   // Angular JIT mode requires the runtime compiler
   if (jit) {
     polyfills.unshift('@angular/compiler');
@@ -749,3 +750,18 @@ function getEsBuildCommonPolyfillsOptions(
 function entryFileToWorkspaceRelative(workspaceRoot: string, entryFile: string): string {
   return './' + toPosixPath(relative(workspaceRoot, entryFile).replace(/.[mc]?ts$/, ''));
 }
+
+/**
+ * Determines if a polyfill path is a local file.
+ * A local file is defined as a path starting with a `.` or having a TypeScript/JavaScript extension.
+ * `zone.js` and its subpaths are specifically excluded and treated as packages.
+ * @param path The polyfill path to check.
+ * @returns true if the path is a local file; false otherwise.
+ */
+function isLocalFile(path: string): boolean {
+  if (path === 'zone.js' || path.startsWith('zone.js/')) {
+    return false;
+  }
+
+  return path.startsWith('.') || /\.[mc]?[jt]sx?$/.test(path);
+}