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/src/modules/auth/hooks/useAuth.ts

@@ -34,7 +34,7 @@ import { currentWorkspaceMemberState } from '@/auth/states/currentWorkspaceMembe
 import { currentWorkspaceMembersState } from '@/auth/states/currentWorkspaceMembersState';
 import { currentWorkspaceState } from '@/auth/states/currentWorkspaceState';
 import { useSignUpInNewWorkspace } from '@/auth/sign-in-up/hooks/useSignUpInNewWorkspace';
-import { useReloadWorkspaceMetadata } from '@/metadata-store/hooks/useReloadWorkspaceMetadata';
+import { useLoadMockedMinimalMetadata } from '@/metadata-store/hooks/useLoadMockedMinimalMetadata';
 import { lastAuthenticatedMethodState } from '@/auth/states/lastAuthenticatedMethodState';
 import { loginTokenState } from '@/auth/states/loginTokenState';
 import {
@@ -42,7 +42,6 @@ import {
   signInUpStepState,
 } from '@/auth/states/signInUpStepState';
 import { workspacePublicDataState } from '@/auth/states/workspacePublicDataState';
-import { coreViewsState } from '@/views/states/coreViewState';
 import { type BillingCheckoutSession } from '@/auth/types/billingCheckoutSession.type';
 import {
   countAvailableWorkspaces,
@@ -88,8 +87,7 @@ export const useAuth = () => {
   const { loadCurrentUser } = useLoadCurrentUser();
   const { clearSseClient } = useClearSseClient();
 
-  const { reloadWorkspaceMetadata, resetToMockedMetadata } =
-    useReloadWorkspaceMetadata();
+  const { loadMockedMinimalMetadata } = useLoadMockedMinimalMetadata();
   const { createWorkspace } = useSignUpInNewWorkspace();
 
   const setSignInUpStep = useSetAtomState(signInUpStepState);
@@ -163,18 +161,17 @@ export const useAuth = () => {
     });
     store.set(loginTokenState.atom, null);
     store.set(signInUpStepState.atom, SignInUpStep.Init);
-    store.set(coreViewsState.atom, []);
 
     await client.clearStore();
     setLastAuthenticateWorkspaceDomain(null);
-    await resetToMockedMetadata();
+    await loadMockedMinimalMetadata();
     navigate(AppPath.SignInUp);
     store.set(isAppEffectRedirectEnabledState.atom, true);
   }, [
     clearSseClient,
     client,
     setLastAuthenticateWorkspaceDomain,
-    resetToMockedMetadata,
+    loadMockedMinimalMetadata,
     navigate,
     store,
   ]);
@@ -305,14 +302,10 @@ export const useAuth = () => {
       setIsAppEffectRedirectEnabled(false);
 
       await loadCurrentUser();
-      await reloadWorkspaceMetadata();
+
+      setIsAppEffectRedirectEnabled(true);
     },
-    [
-      loadCurrentUser,
-      handleSetAuthTokens,
-      reloadWorkspaceMetadata,
-      setIsAppEffectRedirectEnabled,
-    ],
+    [loadCurrentUser, handleSetAuthTokens, setIsAppEffectRedirectEnabled],
   );
 
   const handleGetAuthTokensFromLoginToken = useCallback(