fix(sqlite): add missing agent fields to scanIssues and related queries (#1176)

The scanIssues() function and multiple SQL queries were not selecting or
scanning agent-related fields (hook_bead, role_bead, agent_state, last_activity,
role_type, rig, mol_type) and time-based scheduling fields (due_at, defer_until).

This caused bd list --json to return null for last_activity even when the
database contained valid timestamps, preventing proper agent health monitoring.

Updated files:
- dependencies.go: scanIssues() variable declarations, scan calls, assignments
- queries.go: SearchIssues query
- labels.go: GetIssuesByLabel query
- ready.go: GetReadyWork and GetNewlyUnblockedByClose queries
- transaction.go: GetIssue query, SearchIssues query, scanIssueRow()

Fixes steveyegge/beads#1175

internal/storage/sqlite/queries.go

@@ -2021,7 +2021,9 @@ func (s *SQLiteStorage) SearchIssues(ctx context.Context, query string, filter t
 		       created_at, created_by, owner, updated_at, closed_at, external_ref, source_repo, close_reason,
 		       deleted_at, deleted_by, delete_reason, original_type,
 		       sender, ephemeral, pinned, is_template, crystallizes,
-		       await_type, await_id, timeout_ns, waiters
+		       await_type, await_id, timeout_ns, waiters,
+		       hook_bead, role_bead, agent_state, last_activity, role_type, rig, mol_type,
+		       due_at, defer_until
 		FROM issues
 		%s
 		ORDER BY priority ASC, created_at DESC