feat(alarmas): surface scheduling failures on the alarm card

Wires EstadoAlarmas.ultimaExcepcionPara into PantallaAlarmas: an
alarm with an outstanding scheduling-failure exception now shows a
calm warning line (distinguishing a pre-notice-only failure from the
alarm itself not being registered) with a tap target into the
reliability diagnostics screen. The warning is its own small tap
target nested inside the existing card InkWell, so tap-to-edit,
swipe-to-delete and the hero "Saltar" chip are untouched.

Adds alarmCardSchedulingFailedMessage/alarmCardPreNoticeFailedMessage
to all 13 ARB locales with real per-language translations (verified
against arb_parity_test and arb_anti_copy_test).

lib/l10n/app_en.arb

@@ -842,6 +842,8 @@
     }
   },
   "alarmCardVacationPausedBadge": "Paused for vacation",
+  "alarmCardSchedulingFailedMessage": "This alarm could not be registered with the system, so it may not ring.",
+  "alarmCardPreNoticeFailedMessage": "This alarm is scheduled, but its early reminder could not be set.",
   "alarmDiagnosticsExactAlarmsTitle": "Exact alarm scheduling",
   "alarmDiagnosticsExactAlarmsHint": "Lets the alarm ring at the exact minute you set, even while the phone is asleep.",
   "alarmDiagnosticsNotificationsTitle": "Notifications",