Fix self-hosted license creation in Orbit

Requesting a self-hosted license in Orbit failed with an unauthorized error for every account, blocking new self-hosting evaluations.

• Fixed license creation by resolving your organization from your membership instead of a session flag that was never set
• Added clear error messages for each failure case: signed out, no organization yet, missing admin role, or multiple organizations
• Fixed stale changelog links from search results to land on the changelog index instead of a 404 page