refactor: metadata store cleanup, SSE unification, mock metadata loading & login redirect fix (#18651)

## Summary
- **SSE unification**: Replaced 11 individual SSE effect components with
a single generic `MetadataStoreSSEEffect`
- **Metadata store cleanup**: Merged `metadataCollectionHashesState`
into `metadataStoreState` (currentCollectionHash / draftCollectionHash
per entity), moved `objectMetadataItemsSelector` to `object-metadata`
domain, converted `navigationMenuItemsState` to a derived selector
- **Naming clarity**: Renamed `isAppMetadataReadyState` →
`isMinimalMetadataReadyState`, `MetadataGater` → `MinimalMetadataGater`,
`useIsLogged` → `useHasAccessTokenPair`,
`patchMetadataStoreFromSSEEvent` now takes named object params
- **Mock metadata loading**: Added `generate-navigation-menu-items.ts`
script, rewrote `useLoadMockedMinimalMetadata` to load full
objects/fields/indexes/views/navItems from generated mock data, enabling
proper sign-in background rendering (table columns, view picker,
navigation)
- **Login/logout transitions**: `MinimalMetadataLoadEffect` manages
mocked↔real metadata transitions based on auth state,
`MainContextStoreProvider` computes context on auth pages for view
picker support
- **Login redirect fix**: `handleLoadWorkspaceAfterAuthentication` now
re-enables `isAppEffectRedirectEnabled` after `loadCurrentUser()`
completes, fixing the blocked post-login navigation
- **Dead code removal**: Deleted `useRefreshPageLayouts`,
`useApplyPageLayouts`, `useStaleMetadataEntities`,
`metadataCollectionHashesState`, and all individual SSE effects

## Test plan
- [x] Login from welcome page redirects to companies page
- [x] Logout transitions cleanly to mocked metadata on welcome page
- [x] Sign-in background shows table columns, view picker, and
navigation items
- [x] SSE events still update metadata store entries correctly
- [x] Navigation menu items persist across page refreshes
- [ ] CI: lint, typecheck, tests pass

packages/twenty-server/src/engine/metadata-modules/view-field-group/services/fields-widget-upsert.service.ts

@@ -294,16 +294,17 @@ export class FieldsWidgetUpsertService {
         return [];
       }
 
-      const { viewFieldGroupUniversalIdentifier } =
-        resolveEntityRelationUniversalIdentifiers({
-          metadataName: 'viewField',
-          foreignKeyValues: {
-            viewFieldGroupId: newViewFieldGroupId,
-          },
-          flatEntityMaps: {
-            flatViewFieldGroupMaps: optimisticFlatViewFieldGroupMaps,
-          },
-        });
+      const {
+        viewFieldGroupUniversalIdentifier: _viewFieldGroupUniversalIdentifier,
+      } = resolveEntityRelationUniversalIdentifiers({
+        metadataName: 'viewField',
+        foreignKeyValues: {
+          viewFieldGroupId: newViewFieldGroupId,
+        },
+        flatEntityMaps: {
+          flatViewFieldGroupMaps: optimisticFlatViewFieldGroupMaps,
+        },
+      });
 
       const shouldOverride = isCallerOverridingEntity({
         callerApplicationUniversalIdentifier: applicationUniversalIdentifier,