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-front/scripts/mock-data/generate-minimal-metadata.ts

@@ -0,0 +1,51 @@
+/* oxlint-disable no-console */
+import { graphqlRequest, writeGeneratedFile } from './utils.js';
+
+const MINIMAL_METADATA_QUERY = `
+  query FindMinimalMetadata {
+    minimalMetadata {
+      objectMetadataItems {
+        id
+        nameSingular
+        namePlural
+        labelSingular
+        labelPlural
+        icon
+        isCustom
+        isActive
+        isSystem
+        isRemote
+      }
+      views {
+        id
+        type
+        key
+        objectMetadataId
+      }
+      collectionHashes {
+        collectionName
+        hash
+      }
+    }
+  }
+`;
+
+export const generateMinimalMetadata = async (token: string) => {
+  console.log('Fetching minimal metadata from /metadata ...');
+
+  const data = (await graphqlRequest(
+    '/metadata',
+    MINIMAL_METADATA_QUERY,
+    token,
+  )) as {
+    minimalMetadata: Record<string, unknown>;
+  };
+
+  writeGeneratedFile(
+    'metadata/minimal/mock-minimal-metadata.ts',
+    'mockedMinimalMetadata',
+    'MinimalMetadata',
+    "import { type MinimalMetadata } from '@/metadata-store/types/MinimalMetadata';",
+    data.minimalMetadata,
+  );
+};

packages/twenty-front/scripts/mock-data/generate-navigation-menu-items.ts

@@ -0,0 +1,50 @@
+/* oxlint-disable no-console, lingui/no-unlocalized-strings */
+import { graphqlRequest, writeGeneratedFile } from './utils.js';
+
+const FIND_MANY_NAVIGATION_MENU_ITEMS_QUERY = `
+  query FindManyNavigationMenuItems {
+    navigationMenuItems {
+      id
+      userWorkspaceId
+      targetRecordId
+      targetObjectMetadataId
+      viewId
+      folderId
+      name
+      link
+      icon
+      color
+      position
+      applicationId
+      createdAt
+      updatedAt
+      targetRecordIdentifier {
+        id
+        labelIdentifier
+        imageIdentifier
+      }
+    }
+  }
+`;
+
+export const generateNavigationMenuItems = async (token: string) => {
+  console.log('Fetching navigation menu items from /metadata ...');
+
+  const data = (await graphqlRequest(
+    '/metadata',
+    FIND_MANY_NAVIGATION_MENU_ITEMS_QUERY,
+    token,
+  )) as {
+    navigationMenuItems: Record<string, unknown>[];
+  };
+
+  console.log(`  Got ${data.navigationMenuItems.length} navigation menu items.`);
+
+  writeGeneratedFile(
+    'metadata/navigation-menu-items/mock-navigation-menu-items-data.ts',
+    'mockedNavigationMenuItems',
+    'NavigationMenuItem[]',
+    "import { type NavigationMenuItem } from '~/generated-metadata/graphql';",
+    data.navigationMenuItems,
+  );
+};

packages/twenty-front/scripts/mock-data/generate-object-metadata.ts

@@ -141,7 +141,7 @@ const METADATA_QUERY = `
   }
 `;
 
-export const generateMetadata = async (token: string) => {
+export const generateObjectMetadata = async (token: string) => {
   console.log('Fetching object metadata from /metadata ...');
 
   const metadata = await graphqlRequest('/metadata', METADATA_QUERY, token);