chore: remove IS_APPLICATION_ENABLED feature flag (#19081)

## Summary
- Remove the `IS_APPLICATION_ENABLED` feature flag — application
features are now always enabled
- Remove `@RequireFeatureFlag` decorators and `FeatureFlagGuard` from 7
application resolvers (registration, development, manifest, install,
upgrade, marketplace, oauth)
- Remove frontend feature flag checks: settings navigation visibility,
route protection wrapper, side panel widget type gating, and role
permission flag filtering
- Delete the integration test for disabled-flag behavior
- Clean up seed data, test mocks, and generated schema files

packages/twenty-front/src/modules/settings/hooks/useSettingsNavigationItems.tsx

@@ -75,9 +75,6 @@ const useSettingsNavigationItems = (): SettingsNavigationSection[] => {
     (currentUser?.canImpersonate || currentUser?.canAccessFullAdminPanel) ??
     false;
   const isAIEnabled = useIsFeatureEnabled(FeatureFlagKey.IS_AI_ENABLED);
-  const isApplicationEnabled = useIsFeatureEnabled(
-    FeatureFlagKey.IS_APPLICATION_ENABLED,
-  );
   const isSupportChatConfigured =
     supportChat?.supportDriver === 'FRONT' &&
     isNonEmptyString(supportChat.supportFrontChatId);
@@ -178,9 +175,7 @@ const useSettingsNavigationItems = (): SettingsNavigationSection[] => {
           label: t`Apps`,
           path: SettingsPath.Applications,
           Icon: IconPlug,
-          isHidden:
-            !isApplicationEnabled ||
-            !permissionMap[PermissionFlagType.WORKSPACE],
+          isHidden: !permissionMap[PermissionFlagType.APPLICATIONS],
           modifier: 'new',
         },
         {