fix(mig 134): remove non-existent updated_at column reference (HOTFIX 3)

paliad.proceeding_types has no updated_at column. Removing the
UPDATE ... SET ..., updated_at = now() clause from both up and down
migrations. Third bug in cronus's Slice B1 mig 134 — production
still down.

Verified columns on paliad.proceeding_types via prod-snapshot.sql:
id, code, name, description, jurisdiction, category, default_color,
sort_order, is_active, name_en, display_order, trigger_event_label_de,
trigger_event_label_en, appeal_target (added by this mig).

Refs t-paliad-292, m/paliad#124. No new issue filed — single-line
emergency fix during head's incident response.

internal/db/migrations/134_berufung_unification.down.sql

@@ -24,8 +24,7 @@ SELECT set_config(
 -- ---------------------------------------------------------------
 
 UPDATE paliad.proceeding_types
-   SET is_active = true,
-       updated_at = now()
+   SET is_active = true
  WHERE code IN ('upc.apl.merits', 'upc.apl.cost', 'upc.apl.order');
 
 -- ---------------------------------------------------------------

internal/db/migrations/134_berufung_unification.up.sql

@@ -214,8 +214,7 @@ UPDATE paliad.deadline_rules dr
 -- ---------------------------------------------------------------
 
 UPDATE paliad.proceeding_types
-   SET is_active = false,
-       updated_at = now()
+   SET is_active = false
  WHERE code IN ('upc.apl.merits', 'upc.apl.cost', 'upc.apl.order');
 
 -- ---------------------------------------------------------------