Default master_dashboard_url to https://master.juicerroom.com

Fresh installs point at the master dashboard without manual configuration.
Seeded with INSERT OR IGNORE, so existing databases are untouched.

Note that reporter.ts requires both master_dashboard_url and instance_name
to be non-empty, so this alone does not start reporting — instance_name is
still seeded blank and set per machine.

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

lib/db.ts

@@ -182,7 +182,7 @@ db.exec(`
 const seedSetting = db.prepare(`INSERT OR IGNORE INTO settings (key, value) VALUES (?, ?)`);
 seedSetting.run('max_concurrent_accounts', '5');
 seedSetting.run('tick_interval_seconds', '60');
-seedSetting.run('master_dashboard_url', '');
+seedSetting.run('master_dashboard_url', 'https://master.juicerroom.com');
 seedSetting.run('instance_name', '');
 seedSetting.run('trading_hours', 'full_cme');