feat(events): Wire resource event fetching into sync pipeline (bd-1ep)

Enqueue resource_events jobs for all issues/MRs after discussion sync,
then drain the queue by fetching state/label/milestone events from GitLab
API and storing them via transaction-based wrappers. Adds progress events,
count tracking through orchestrator->ingest->sync result chain, and
respects fetch_resource_events config flag. Includes clippy fixes across
codebase from parallel agent work.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tests/migration_tests.rs

@@ -26,7 +26,7 @@ fn apply_migrations(conn: &Connection, through_version: i32) {
 
         let sql = std::fs::read_to_string(entries[0].path()).unwrap();
         conn.execute_batch(&sql)
-            .expect(&format!("Migration {} failed", version));
+            .unwrap_or_else(|e| panic!("Migration {} failed: {}", version, e));
     }
 }