Add issue change history and daily issue stats

Issue changes are recorded per field in the issue_change table, in the same
transaction as the issue itself. The new history module exposes:
- GET /api/issues/:issueId/history — change timeline grouped by save
- GET /api/issues/stats/daily — created, status transitions and status
  snapshot per day, with time zone support

The migration backfills history for existing issues. Setting a field to its
current value no longer bumps updatedAt or emits issue.updated.

src/modules/issue/application/use-cases/update-issue/update-issue.use-case.spec.ts

@@ -72,6 +72,14 @@ describe('UpdateIssueUseCase', () => {
     expect(repository.update).toHaveBeenCalledTimes(1);
   });
 
+  it('passes the acting user to the repository as the author of the changes', async () => {
+    vi.mocked(repository.findById).mockResolvedValue(buildIssue());
+
+    await useCase.execute(new UpdateIssueCommand(1, 'user-7', undefined, undefined, 'DONE'));
+
+    expect(repository.update).toHaveBeenCalledWith(expect.any(Issue), 'user-7');
+  });
+
   it('assigns and unassigns depending on the assignee value', async () => {
     vi.mocked(repository.findById).mockResolvedValue(buildIssue());
 

src/modules/issue/application/use-cases/update-issue/update-issue.use-case.ts

@@ -57,7 +57,7 @@ export class UpdateIssueUseCase {
       issue.updateDueDate(command.dueDate);
     }
 
-    await this.issueRepository.update(issue);
+    await this.issueRepository.update(issue, command.userId);
     const dto = await this.issueUserExpander.expand(issue);
 
     if (issue.assignee) {