fix(auth): fallback to direct cleanup when tenant context is unavailable

When CurrentTenant(ctx) fails in the session cleanup worker (no tenant
in background context), fall back to DeleteExpired without RLS instead
of logging an error and skipping cleanup entirely. This is safe as the
query only deletes expired sessions and runs as DB owner.

Author: btouchard

backend/internal/infrastructure/auth/session_worker.go

@@ -164,16 +164,19 @@ func (w *SessionWorker) performCleanup() {
 	if w.db != nil && w.tenants != nil {
 		tenantID, tenantErr := w.tenants.CurrentTenant(ctx)
 		if tenantErr != nil {
-			logger.Logger.Error("Failed to get tenant for session cleanup",
-				"error", tenantErr.Error())
-			return
+			// No tenant in context (background worker in multi-tenant mode).
+			// Fall back to direct cleanup without RLS — safe because this only
+			// deletes expired sessions and runs as the DB owner role.
+			logger.Logger.Debug("No tenant context for session cleanup, using direct cleanup",
+				"reason", tenantErr.Error())
+			deleted, err = w.sessionRepo.DeleteExpired(ctx, w.cleanupAge)
+		} else {
+			err = tenant.WithTenantContext(ctx, w.db, tenantID, func(txCtx context.Context) error {
+				var cleanupErr error
+				deleted, cleanupErr = w.sessionRepo.DeleteExpired(txCtx, w.cleanupAge)
+				return cleanupErr
+			})
 		}
-
-		err = tenant.WithTenantContext(ctx, w.db, tenantID, func(txCtx context.Context) error {
-			var cleanupErr error
-			deleted, cleanupErr = w.sessionRepo.DeleteExpired(txCtx, w.cleanupAge)
-			return cleanupErr
-		})
 	} else {
 		// No RLS - direct repository access (for tests)
 		deleted, err = w.sessionRepo.DeleteExpired(ctx, w.cleanupAge)