fix(alarmas): show which days a weekday alarm actually fires on

The alarms list showed a generic "Días" label for a diasSemana alarm
instead of its actual configured days. Render the real recurrence (e.g.
"Lun, Mié, Vie") by reusing the SAME per-day abbreviation the editor's own
day-picker circles already use -- no new formatting scheme, no new ARB
keys for the days themselves.

Also surface fade/volume/vacation-pause state on the card, each only when
it is a genuinely useful deviation from the common case: a fade badge when
fadeInSegundos > 0 (reusing the existing alarmFadeInLabel key), a volume
percentage when it differs from the 85% default, and a vacation-paused
badge when the alarm is both configured to pause and a vacation range is
currently active (mirrors the exact predicate ServicioProgramacionAlarmas
already uses). One compact line, not a badge per field.

Fixes a text-collision regression in pantalla_alarmas_editor_test.dart:
opening the editor for an alarm whose own day now renders on its card
(e.g. "Lun") made a bare find.text(weekday) ambiguous against the editor's
day-picker circle with the same label -- scoped that finder to the
BottomSheet subtree.

test/pantallas/pantalla_alarmas_editor_test.dart

@@ -190,9 +190,26 @@ void main() {
       expect(antes, isNot(l10n.alarmNoNextExecution));
 
       // Lunes -> Martes: la fecha calculada SIEMPRE cambia, sea cual sea hoy.
-      await tester.tap(find.text(l10n.weekdayShortTuesday));
+      //
+      // Item 5: the alarm CARD underneath now also renders the real day
+      // abbreviation ("Lun") for a diasSemana alarm, so a bare
+      // `find.text(...)` for a weekday letter is ambiguous while the
+      // editor sheet is open on top of the list — scope to the sheet's own
+      // BottomSheet subtree to target the day-picker circle specifically.
+      final hojaEditor = find.byType(BottomSheet);
+      await tester.tap(
+        find.descendant(
+          of: hojaEditor,
+          matching: find.text(l10n.weekdayShortTuesday),
+        ),
+      );
       await tester.pumpAndSettle();
-      await tester.tap(find.text(l10n.weekdayShortMonday));
+      await tester.tap(
+        find.descendant(
+          of: hojaEditor,
+          matching: find.text(l10n.weekdayShortMonday),
+        ),
+      );
       await tester.pumpAndSettle();
 
       final despues = _textoPreview(tester);