[Agent] Domain settings hardcode hollahoop.app hostname

Agent brief

Category: bug | Severity: low | Effort: XS

Problem

Custom domain settings UI hardcodes hollahoop.app in CNAME instructions instead of reading from env/config.

Repro

1. Admin → Project → Domain settings
2. CNAME target always shows hollahoop.app even on self-hosted/staging

Files

• Grep hollahoop.app in domain settings components

Acceptance criteria

• CNAME/host values use NEXT_PUBLIC_APP_URL or dedicated env
• Staging shows correct hostname

Suggested approach

Use existing getAppOrigin() helper if present.