fix(companion): make reference-app exports reproducible by default

No diagram change needed: this change only makes generated reference-app timestamps deterministic and adds an override flag.

scripts/export-companion-reference-apps.ts

@@ -1,6 +1,8 @@
 import { resolve } from 'node:path';
 import { generateReferenceCompanionApps } from '../src/companion/index.js';
 
+const DEFAULT_GENERATED_AT = '2026-02-27T00:00:00.000Z';
+
 function getArg(name: string): string | undefined {
   const idx = process.argv.indexOf(name);
   if (idx < 0) {
@@ -16,10 +18,16 @@ function getArg(name: string): string | undefined {
 async function main(): Promise<void> {
   const outputDir = resolve(getArg('--output') ?? 'apps/companion');
   const gatewayUrl = getArg('--url') ?? 'ws://127.0.0.1:18800';
+  const generatedAtArg = getArg('--generated-at');
+  const generatedAt = new Date(generatedAtArg ?? DEFAULT_GENERATED_AT);
+  if (Number.isNaN(generatedAt.getTime())) {
+    throw new Error(`Invalid --generated-at value: ${generatedAtArg}`);
+  }
 
   const result = await generateReferenceCompanionApps({
     outputDir,
     gatewayUrl,
+    generatedAt,
   });
 
   console.log(`Generated companion reference apps in ${result.rootDir}`);
@@ -28,6 +36,7 @@ async function main(): Promise<void> {
   }
   console.log(`- macos-app: ${result.macosMenuBarAppDir}`);
   console.log(`- readme: ${result.readmePath}`);
+  console.log(`- generatedAt: ${generatedAt.toISOString()}`);
 }
 
 main().catch((error: unknown) => {