Ajoute date debut et date de fin

Signed-off-by: Gato <cedric@goutailler-olivier.fr>

src/app/issues/issues.store.spec.ts

@@ -10,6 +10,8 @@ const makeIssue = (overrides: Partial<IssueEntity> = {}): IssueEntity => ({
   assignee: '',
   epic: '',
   name: 'Test Issue',
+  startDate: '',
+  endDate: '',
   dueDate: '',
   description: '',
   estimatedTime: null,
@@ -156,6 +158,31 @@ describe('IssuesStore', () => {
       await p;
       expect(store.getById(994)?.estimatedTime).toBeNull();
     });
+
+    it('defaults startDate to empty string when missing in API response', async () => {
+      const issue = { ...makeIssue({ id: 0 }), startDate: undefined } as any;
+      const p = store.upsert(issue);
+      httpMock.expectOne({ method: 'POST', url: `${API_BASE_URL}/issues` }).flush({ ...makeIssue({ id: 993 }), startDate: undefined });
+      await p;
+      expect(store.getById(993)?.startDate).toBe('');
+    });
+
+    it('defaults endDate to empty string when missing in API response', async () => {
+      const issue = { ...makeIssue({ id: 0 }), endDate: undefined } as any;
+      const p = store.upsert(issue);
+      httpMock.expectOne({ method: 'POST', url: `${API_BASE_URL}/issues` }).flush({ ...makeIssue({ id: 992 }), endDate: undefined });
+      await p;
+      expect(store.getById(992)?.endDate).toBe('');
+    });
+
+    it('preserves startDate and endDate when provided', async () => {
+      const issue = makeIssue({ id: 0, startDate: '2026-01-01', endDate: '2026-01-31' });
+      const p = store.upsert(issue);
+      httpMock.expectOne({ method: 'POST', url: `${API_BASE_URL}/issues` }).flush(makeIssue({ id: 991, startDate: '2026-01-01', endDate: '2026-01-31' }));
+      await p;
+      expect(store.getById(991)?.startDate).toBe('2026-01-01');
+      expect(store.getById(991)?.endDate).toBe('2026-01-31');
+    });
   });
 
   describe('deleteById', () => {