fix: add _repo fallback to events repo filter for github-repo commits

The events query's COALESCE for github source was missing _repo,
so per-repo commit events from github_repo had no repo match and
project pages showed 0 activities.

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

crates/moments-data/src/lib.rs

@@ -58,7 +58,8 @@ impl EventReader for PgStore {
               AND ($6::text IS NULL OR (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',