Domains auto-evolve from project issue signals

Hive can now discover and create domains from the work signals that projects generate. Previously, GitHub issue syncing only looked at repositories reachable through existing domains, so a project with repositories but no domains could not feed issue signals into domain evolution. Now the issue syncer polls repositories connected to any project, and domain evolution uses project context from GitHub issues, Grafana alerts, and specs to propose and link new domains. This lets operators keep projects as the manual boundary and let domains grow organically from real work signals, without setting up domains before issue ingestion starts.