feat: hostname-aware window title (#82)

Set the browser tab title to codeman:${hostname} instead of the bare
"Codeman" literal. Useful for users running multiple Codeman instances
across hosts (laptop, dev box, NAS) — the OS hostname disambiguates
which tab points at which backend.

Implementation:

- src/cli.ts: new --title-hostname <hostname> flag overrides the
  detected hostname (handy for cosmetic naming or when os.hostname()
  returns something noisy).
- src/web/server.ts: WebServer now accepts an optional titleHostname
  constructor arg (defaults to os.hostname()), composes
  windowTitle = codeman:${titleHostname}, and serves / and
  /index.html by templating that title into the cached index.html
  template (with HTML escaping of the title text).
- src/web/public/notification-manager.js: title-flash logic now uses
  this.originalTitle instead of the hardcoded "Codeman" literal, so
  the tab flash respects the per-host title.
- scripts/browser-comparison.mjs + test/file-link-click.test.ts:
  expectations updated from === "Codeman" to a startsWith("codeman:")
  predicate so they pass regardless of host.

The new index.html templating is intentionally narrow — it only
substitutes the <title> tag and continues to serve everything else
from the static template. No JS-side title injection, so it works
without JavaScript and shows the correct title from the very first
paint.

Note: test/file-link-click.test.ts shows ~49 prettier-reformat lines
that are not part of the feature — they are pre-existing prettier
debt that the pre-commit hook required me to clear. The single
behavioral change is the browserAvailable line.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/cli.ts

@@ -485,16 +485,18 @@ program
   .description('Start the web interface')
   .option('-p, --port <port>', 'Port to listen on', '3000')
   .option('--https', 'Enable HTTPS with self-signed certificate (only needed for remote access, not localhost)')
+  .option('--title-hostname <hostname>', 'Override the hostname shown in the browser title')
   .action(async (options) => {
     const { startWebServer } = await import('./web/server.js');
     const port = parseInt(options.port, 10);
     const https = !!options.https;
+    const titleHostname = options.titleHostname;
     const protocol = https ? 'https' : 'http';
 
     console.log(chalk.cyan(`Starting Codeman web interface on port ${port}${https ? ' (HTTPS)' : ''}...`));
 
     try {
-      const server = await startWebServer(port, https);
+      const server = await startWebServer(port, https, false, titleHostname);
       console.log(chalk.green(`\n✓ Web interface running at ${protocol}://localhost:${port}`));
       if (https) {
         console.log(chalk.yellow('  Note: Accept the self-signed certificate in your browser on first visit'));