fix: stamp _repo into github-repo commit payloads for project attribution

The /repos/{owner}/{repo}/commits endpoint doesn't include repo info
in its response. Without _repo in the payload, these commits were
invisible to the projects query. Add _repo to parse_commit and include
it in the COALESCE chain for github source repo extraction.

After deploy, reset github-repo poller state to re-ingest with _repo:
  DELETE FROM poller_state WHERE source LIKE 'github-repo%';

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

crates/moments-data/src/lib.rs

@@ -145,7 +145,8 @@ impl EventReader for PgStore {
                     CASE source
                         WHEN 'github' THEN COALESCE(
                             payload->'repo'->>'name',
-                            payload->'repository'->>'full_name'
+                            payload->'repository'->>'full_name',
+                            payload->>'_repo'
                         )
                         WHEN 'gitea' THEN COALESCE(
                             payload->'repo'->>'full_name',