fix(BA-5829): drop explicit AppConfigScopeType GQL registration

`gql_enum(...)` returns a wrapped enum class, which Strawberry registers
under `"AppConfigScopeType"`. Other GQL modules use the bare DTO enum as
a field annotation, and Strawberry auto-registers that under the same
name on first encounter — failing the schema build with `Type
AppConfigScopeType is defined multiple times`.

Drop the explicit registration and let Strawberry auto-register from
field references; re-export the GQL alias as a plain rebind so existing
`AppConfigScopeTypeGQL` imports keep working.

Author: jopemachine

src/ai/backend/manager/api/gql/app_config_fragment/types/node.py

@@ -12,21 +12,17 @@
 from ai.backend.common.meta.meta import NEXT_RELEASE_VERSION
 from ai.backend.manager.api.gql.decorators import (
     BackendAIGQLMeta,
-    gql_enum,
     gql_field,
     gql_pydantic_type,
 )
 from ai.backend.manager.api.gql.pydantic_compat import PydanticOutputMixin
 
-# Register the shared DTO enum as a Strawberry type.
-AppConfigScopeTypeGQL = gql_enum(
-    BackendAIGQLMeta(
-        added_version=NEXT_RELEASE_VERSION,
-        description="App-config scope type.",
-    ),
-    AppConfigScopeType,
-    name="AppConfigScopeType",
-)
+# The shared DTO enum is auto-registered by Strawberry the first time it
+# is referenced as a typed field. Re-export under the ``GQL`` suffix so
+# other modules can write `from ... import AppConfigScopeTypeGQL`. Calling
+# `strawberry.enum(...)` here would clash with that auto-registration
+# under the same `"AppConfigScopeType"` name.
+AppConfigScopeTypeGQL = AppConfigScopeType
 
 
 @gql_pydantic_type(
@@ -42,8 +38,6 @@ class AppConfigFragmentGQL(PydanticOutputMixin[AppConfigFragmentNode]):
     scope_type: AppConfigScopeType = gql_field(description="Scope type.")
     scope_id: str = gql_field(description="Scope id.")
     name: str = gql_field(description="Policy name (FK to app_config_policies).")
-    extra_config: JSON | None = gql_field(
-        description="Raw configuration payload, or null."
-    )
+    extra_config: JSON | None = gql_field(description="Raw configuration payload, or null.")
     created_at: datetime = gql_field(description="Creation timestamp.")
     updated_at: datetime | None = gql_field(description="Last update timestamp.")