generate index.html's absolute URLs from PUBLIC_URL

index.html hardcoded the deployment's domain in eight places, so every instance
had to carry its own edit of the file — the only thing separating the rezio
branch from master.

The tags genuinely need absolute URLs. OpenGraph is fetched standalone by
crawlers, and Bun's HTML bundler treats a root-relative href as an asset to
resolve on disk, failing the build with "Could not resolve: /favicon.ico" —
external URLs are the only form it passes through untouched.

Bun's HTML import offers no substitution hook, so scripts/gen-index.ts swaps
__PUBLIC_URL__ for the value in .env and writes index.gen.html, which the server
imports. index.html is the tracked template and is now identical on every
deployment; index.gen.html is gitignored. predev/prestart run the generator, and
it is idempotent so --watch does not loop.

Substituting also fixes the manifest: an absolute URL puts its fetch in CORS
mode, which failed whenever the hardcoded domain was not the serving origin.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

scripts/gen-index.ts

@@ -0,0 +1,48 @@
+#!/usr/bin/env bun
+// Generates src/apps/officer-web/index.gen.html from index.html, substituting __PUBLIC_URL__ with
+// PUBLIC_URL from .env.
+//
+// The OpenGraph tags need absolute URLs — crawlers fetch the page standalone and cannot resolve
+// relative ones — but hardcoding the domain forces every deployment to carry its own edit of
+// index.html. Bun's HTML import offers no substitution hook, so the swap happens here and the server
+// imports the generated file. index.gen.html is gitignored; index.html is the tracked template and
+// is identical on every instance.
+
+import { existsSync } from 'node:fs';
+import { dirname, join, resolve } from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const root = resolve(dirname(fileURLToPath(import.meta.url)), '..');
+const template = join(root, 'src/apps/officer-web/index.html');
+const output = join(root, 'src/apps/officer-web/index.gen.html');
+
+// The server reads .env through --env-file, but this script runs standalone.
+const envPath = join(root, '.env');
+if (!process.env.PUBLIC_URL && existsSync(envPath)) {
+  for (const line of (await Bun.file(envPath).text()).split('\n')) {
+    const match = line.match(/^\s*PUBLIC_URL\s*=\s*(.*)$/);
+    if (match) process.env.PUBLIC_URL = match[1]!.trim().replace(/^["']|["']$/g, '');
+  }
+}
+
+const publicUrl = (process.env.PUBLIC_URL ?? '').replace(/\/+$/, '');
+if (!publicUrl) {
+  console.error('[gen-index] PUBLIC_URL is not set — set it in .env (e.g. https://officer.example.com)');
+  process.exit(1);
+}
+
+const html = await Bun.file(template).text();
+const generated = html.replaceAll('__PUBLIC_URL__', publicUrl);
+
+if (generated.includes('__PUBLIC_URL__')) {
+  console.error('[gen-index] substitution left placeholders behind');
+  process.exit(1);
+}
+
+// Only write when the content actually changes, so `bun --watch` does not restart in a loop.
+if (existsSync(output) && (await Bun.file(output).text()) === generated) {
+  console.log(`[gen-index] up to date (${publicUrl})`);
+} else {
+  await Bun.write(output, generated);
+  console.log(`[gen-index] wrote index.gen.html (${publicUrl})`);
+}