feat: bulk edit tickets

Select several tickets in the backlog and change their status, assignee,
sprint, priority or labels at once. Each ticket goes through the normal
rules and may refuse on its own; the result says which did.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

libs/api/tracker/application/src/lib/issues.service.ts

@@ -16,6 +16,11 @@ import { DetachFileCommand } from './commands/detach-file.command';
 import { WatchIssueCommand } from './commands/watch-issue.command';
 import { SetIssueParentCommand } from './commands/set-issue-parent.command';
 import { RankIssueCommand } from './commands/rank-issue.command';
+import {
+  BulkChange,
+  BulkResult,
+  BulkUpdateIssuesCommand,
+} from './commands/bulk-update-issues';
 import {
   AddChecklistItemCommand,
   RemoveChecklistItemCommand,
@@ -231,6 +236,17 @@ export class IssuesService {
     );
   }
 
+  /** The same change on several tickets; each one may succeed or not. */
+  bulkUpdate(
+    actorId: string,
+    issueIds: string[],
+    change: BulkChange,
+  ): Promise<BulkResult> {
+    return this.commandBus.execute(
+      new BulkUpdateIssuesCommand(actorId, issueIds, change),
+    );
+  }
+
   addChecklistItem(
     actorId: string,
     issueId: string,