docs: clarify HTTP is fine for localhost, HTTPS only for remote

Localhost is treated as a secure context by browsers, so notifications
and all browser APIs work without HTTPS. Updated README, CLI help,
install script, and systemd service to default to HTTP.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/cli.ts

@@ -493,7 +493,7 @@ program
   .command('web')
   .description('Start the web interface')
   .option('-p, --port <port>', 'Port to listen on', '3000')
-  .option('--https', 'Enable HTTPS with a self-signed certificate (enables browser Notifications API)')
+  .option('--https', 'Enable HTTPS with self-signed certificate (only needed for remote access, not localhost)')
   .action(async (options) => {
     const { startWebServer } = await import('./web/server.js');
     const port = parseInt(options.port, 10);