Domains can now evolve from GitHub issue signals on projects without existing domains

GitHub issue syncing now looks up repositories through the projects they belong to, not only through existing domains, so a manually created project with repositories starts collecting issue signals even before any domains exist. Domain evolution now receives that project context (alongside signals from Grafana alerts and specs), and when the evolution agent proposes a new domain it can return project identifiers that Hive validates and links back to the matching projects. Operators can treat projects as the durable boundary and let domains grow from the work signals those projects produce, including the zero-domain bootstrap case.