feat: isolate apartment portfolios by landlord (#25)

frontend/src/app/components/apartment-form/apartment-form.spec.ts

@@ -31,6 +31,24 @@ describe('ApartmentForm', () => {
     expect(saved).not.toHaveBeenCalled();
   });
 
+  it('rejects whitespace-only fields before the backend does', () => {
+    const fixture = TestBed.createComponent(ApartmentForm);
+    const form = fixture.componentInstance;
+    const saved = vi.fn();
+    form.saved.subscribe(saved);
+    form.apartmentModel.set({
+      name: '   ',
+      address: '  ',
+      purchasePrice: 250000,
+      description: '',
+    });
+
+    form.save();
+
+    expect(form.error()).toContain('Veuillez remplir tous les champs obligatoires');
+    expect(saved).not.toHaveBeenCalled();
+  });
+
   it('emits a trimmed apartment draft when valid', () => {
     const fixture = TestBed.createComponent(ApartmentForm);
     const form = fixture.componentInstance;