The server root (/) needs a proper default page. Currently it's a placeholder.

The page should adapt to server mode:

Multi-user server — intro text, signup/login buttons, branding
Single-user pod — personal homepage, link to profile/WebID
Dev/testing — server info, version, enabled features

Considerations:

• Most valuable URL in the pod — needs careful thought
• Part of first-time setup and onboarding
• Should be low barrier (as discussed with ewingson)
• Template should be customizable per server but have a good default
• Could detect mode from config (--single-user, --idp, etc.)