Add gitUrl and gitBranch fields to kilo_meta so shared sessions
include repository context. Resolves the best remote (origin > single
available > upstream) and fetches the URL with a 10s in-flight cache.
Unify ingest queue and session close reasons via `Session.CloseReason` and
ensure `TurnOpen`/`TurnClose` publishing is awaited; mark close reason as
`error` on unexpected exceptions and handle abort-induced stops correctly.
Add ingest queue tests for stable-key coalescing of session open/close and for
including `?v=1` on flush requests.