fix: pre-fix trigger edited_by for superadmins not in workspace (#8669)

Add a migration that runs just before 20260318000000 (add_permissioned_as).
For each trigger table, if the email column still exists, update edited_by
to the trigger's email when the user is not in the workspace but is a
superadmin. This ensures the subsequent permissioned_as migration stores
the raw email instead of an invalid u/{username} reference.

If 20260318000000 was already applied, the migration is a no-op (email
column is gone, guarded by information_schema check).

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

backend/migrations/20260317999999_fix_trigger_superadmin_edited_by.down.sql

@@ -0,0 +1 @@
+-- No-op: this migration is a data fixup and cannot be reversed.

backend/migrations/20260317999999_fix_trigger_superadmin_edited_by.up.sql

@@ -0,0 +1,48 @@
+-- Pre-fix: before permissioned_as migration drops the email column, update edited_by
+-- for triggers where the user (edited_by) is not in the workspace but is a superadmin.
+-- This ensures the subsequent 20260318000000 migration stores the raw email as permissioned_as
+-- (via the `edited_by LIKE '%@%'` branch).
+-- For instances that already applied 20260318000000, this is a no-op (email column is gone);
+-- the 20260401000000 migration handles those as a fallback.
+
+DO $$
+DECLARE
+    trigger_table TEXT;
+    has_email BOOLEAN;
+BEGIN
+    FOREACH trigger_table IN ARRAY ARRAY[
+        'http_trigger',
+        'websocket_trigger',
+        'postgres_trigger',
+        'mqtt_trigger',
+        'kafka_trigger',
+        'nats_trigger',
+        'sqs_trigger',
+        'gcp_trigger',
+        'email_trigger'
+    ]
+    LOOP
+        SELECT EXISTS (
+            SELECT 1 FROM information_schema.columns
+            WHERE table_name = trigger_table AND column_name = 'email'
+        ) INTO has_email;
+
+        IF has_email THEN
+            EXECUTE format($q$
+                UPDATE %I t
+                SET edited_by = t.email
+                WHERE NOT EXISTS (
+                    SELECT 1 FROM usr u
+                    WHERE u.username = t.edited_by
+                      AND u.workspace_id = t.workspace_id
+                )
+                AND EXISTS (
+                    SELECT 1 FROM password p
+                    WHERE p.email = t.email
+                      AND p.super_admin = true
+                )
+            $q$, trigger_table);
+        END IF;
+    END LOOP;
+END;
+$$;