fix: Add root path redirect to /admin in Trinity Console

WHAT WAS DONE:
- Added app.get('/', ...) route handler that redirects to /admin
- Placed after health check, before CSRF middleware

WHY:
- Holly and Meg were getting 'cannot GET /' error when accessing
  discord-bot.firefrostgaming.com without the /admin path
- Michael had an active session from earlier testing so didn't notice
- Trinity Console only had /admin routes defined, no root handler

HOW IT WORKS:
- Users visiting https://discord-bot.firefrostgaming.com/ now auto-redirect
  to https://discord-bot.firefrostgaming.com/admin
- Simplifies access - no need to remember /admin suffix

IMPACT:
- Fixes immediate access issue for The Trinity
- Better UX - root domain works as expected
- No security impact - still requires Discord OAuth

FILES MODIFIED:
- services/arbiter-3.0/src/index.js (2 lines added)

TESTED:
- Deployed to Command Center (63.143.34.217)
- Service restarted successfully
- Holly and Meg can now access Trinity Console

Signed-off-by: Claude (Chronicler #52) <claude@firefrostgaming.com>

services/arbiter-3.0/src/index.js

@@ -64,6 +64,9 @@ app.get('/health', (req, res) => {
     });
 });
 
+// Root redirect to admin
+app.get('/', (req, res) => res.redirect('/admin'));
+
 // CSRF Protection (session-based)
 const csrfProtection = csrf({ cookie: false });