feat(alarmas): rewrite alarm editor with inline time widget

Replace the native showTimePicker dialog in the alarm editor sheet with
a giant inline HH:MM editor (drag/tap to adjust, wraps at 23:59-00:00).
Weekday circles now render unconditionally (disabled outside weekly
mode) instead of being gated behind an `if`.

The date field, fallback-station picker, and sound dropdown are not
dropped: per resolution 3 they move into a collapsed "Advanced" section
so the mockup's weekday-circles-only layout does not lose capability.
Volume/fade-in sliders get a cosmetic type-scale restyle only.

size:exception: 993 changed lines (891+/102-) against the 500-650
forecast - lib/ production code alone is 429 lines, within band; new
test files and 13 regenerated l10n/gen files account for the rest, the
same pattern every prior work unit in this branch has hit.

test/pantallas/pantalla_alarmas_editor_test.dart

@@ -242,6 +242,15 @@ void main() {
     (tester) async {
       await _abrirEditor(tester);
 
+      // WU10 correction: the fallback-station field moved into the
+      // collapsed "Advanced" section (native-alarms delta — Alarm Editor
+      // Preserves Date, Fallback Station, and Sound Fields). It must be
+      // expanded first — a collapsed `ExpansionTile` does not build its
+      // children, so `find.byKey` would otherwise find nothing.
+      await tester.ensureVisible(find.text(l10n.alarmAdvancedSectionTitle));
+      await tester.tap(find.text(l10n.alarmAdvancedSectionTitle));
+      await tester.pumpAndSettle();
+
       await tester.ensureVisible(
         find.byKey(const ValueKey('alarm-fallback-station-field')),
       );