feat(alarmas): replace one-line reliability button with full diagnostics screen

Surface all six DiagnosticoAlarmasAndroid fields instead of three: the
battery-optimization exemption and native pending-alarm count were
already collected but silently dropped by the old widget. Each failing
signal now offers a "Fix this" action that opens the right system
settings screen (exact alarms, notifications, full-screen intent,
battery optimization), guarded by SDK level and never crashing when a
ROM lacks that screen. Manufacturers known for aggressive background
killing (Xiaomi/Redmi/POCO, Huawei, Oppo, Vivo, OnePlus, Samsung) get
an honest explanation that Autostart must be enabled manually, since
there is no API to detect or grant it.

Notifications now deep-links straight to
ACTION_APP_NOTIFICATION_SETTINGS via a new openNotificationSettings
native method, instead of reusing the runtime permission popup meant
for first-time alarm creation.

New copy is added to all 13 ARB locales with real per-language
translations (not Spanish copies), verified by the ARB parity and
anti-copy tests plus the corruption scanner.

test/l10n/identical_value_allowlist.dart

@@ -272,4 +272,8 @@ const Set<(String locale, String key)> identicalValueAllowlist = {
     'pt',
     'searchResultsCount',
   ), // WU18 new key (task 18.3) -- "resultado(s)" is an es/pt cognate
+  (
+    'pt',
+    'alarmDiagnosticsManufacturerLabel',
+  ), // fix/alarmas-fiabilidad new key -- "Fabricante" is identical in pt/es
 };