feat: «Recordármelo», a reminder of a ticket only for me

On a ticket, «Recordármelo» offers in an hour, this evening, tomorrow or
next Monday at 9, in a week, or any date and time, with an optional note.
The ticket shows the waiting one («Te lo recordaré el mié 21 a las 9:00»)
to change or drop. Every minute a scheduler tells the ones whose time
came as a REMINDER notification (bell, push, e-mail), once, and forgets
those whose ticket went to the trash or out of reach. One per person and
ticket, private, no history (Mongo `issue_reminders`).

API: setReminder / clearReminder, Issue.myReminder, myReminders;
PUT/DELETE /api/issues/{issue}/reminder, GET /api/me/reminders. MCP:
remind_me.

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

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

@@ -1417,3 +1417,13 @@ export class AlertOutcomeDto {
   @ApiProperty({ type: String, nullable: true, example: 'WEB-42' })
   issueKey!: string | null;
 }
+
+export class IssueReminderDto {
+  @ApiProperty({ format: 'date-time' }) at!: string;
+  @ApiProperty({ type: String, nullable: true }) note!: string | null;
+}
+
+export class ReminderOnIssueDto {
+  @ApiProperty({ type: IssueReminderDto }) reminder!: IssueReminderDto;
+  @ApiProperty({ type: () => IssueDto }) issue!: IssueDto;
+}