fix(migration): use CAST instead of :: for jsonb type cast in seed data

SQLAlchemy's text() interprets ::jsonb as a named parameter binding.
Use CAST(:profile_data AS jsonb) to avoid the collision.

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

backend/alembic/versions/038_snmp_profiles_table.py

@@ -662,7 +662,7 @@ def upgrade() -> None:
                      category, profile_data, is_system)
                 VALUES
                     (NULL, :name, :description, :sys_object_id, :vendor,
-                     :category, :profile_data::jsonb, TRUE)
+                     :category, CAST(:profile_data AS jsonb), TRUE)
             """),
             {
                 "name": profile["name"],