feat: an ordered backlog

A Backlog tab lists the tickets still to start in the order the team will
take them; drag them, or use the arrows, to reorder. Moving a ticket only
rewrites that ticket's rank, read from the event store, and board columns
follow the same order.

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

libs/api/tracker/presenters/src/lib/http/dto/responses.dto.ts

@@ -179,6 +179,11 @@ export class IssueDto {
     description: 'The epic or ticket this one breaks down',
   })
   parent!: IssueParentDto | null;
+  @ApiProperty({
+    description:
+      'Place in the backlog and its board column (ascending, as text)',
+  })
+  rank!: string;
   @ApiProperty({ type: [ChecklistItemDto] }) checklist!: ChecklistItemDto[];
   @ApiProperty() commentCount!: number;
   @ApiProperty({ format: 'date-time' }) createdAt!: string;