fix: restore isCustom gate in metadata label resolvers (#21432)

## Context

#21228 removed the stored `isCustom` column and, with it, the `isCustom`
early-return in `resolveObjectMetadataStandardOverride` /
`resolveFieldMetadataStandardOverride`, on the assumption that falling
through the `standardOverrides` checks was equivalent.

It isn't: custom object/field labels now reach the Lingui lookup. A
custom label that collides with a standard catalog string (e.g. a custom
field labeled "Status") gets translated for non-English locales against
the user's intent, and every other custom label pays a hash + catalog
miss — and, in production, an "Uncompiled message detected" warning
(#21415) — on each metadata resolution.

## Fix

Restore the gate. `isCustom` is no longer stored, so call sites that
build the resolver input from flat entities (dataloader,
minimal-metadata, view controller, command-menu-item navigation context)
derive it via `belongsToTwentyStandardApp`; GraphQL resolvers keep
passing DTOs, which already carry the derived value.

## Testing

- Unit tests for both resolvers, including a new regression test: a
custom label matching a standard catalog entry is returned verbatim,
Lingui never called.

---------

Co-authored-by: Weiko <corentin@twenty.com>

packages/twenty-server/src/engine/metadata-modules/command-menu-item/utils/build-navigation-interpolation-context.util.ts

@@ -9,6 +9,7 @@ export type NavigationInterpolationObjectMetadata = {
   labelSingular: string;
   description?: string | null;
   icon?: string | null;
+  isCustom: boolean;
   standardOverrides?: ObjectStandardOverridesDTO | null;
 };
 
@@ -26,6 +27,7 @@ export const buildNavigationInterpolationContext = ({
     labelSingular: objectMetadata.labelSingular,
     description: objectMetadata.description ?? undefined,
     icon: objectMetadata.icon ?? undefined,
+    isCustom: objectMetadata.isCustom,
     standardOverrides: objectMetadata.standardOverrides ?? undefined,
   };