fix(alarma-sonando): date line, additive snooze qualifier

Audit 9.4 (t4:419): "Lunes, 3 de agosto" now renders between the
schedule pill and the hero time -- purely additive, a new sibling
Text touching neither element. New formato_fechas.dart helper
fechaLargaConDiaSemana (locale-aware via DateFormat.MMMMEEEEd).

Audit 9.10 (t4:433): the highlighted snooze tile gains a "usual"
qualifier (new ARB key alarmSnoozeUsualLabel) alongside the original
flat label -- resolved DIFFERENTLY than its sibling 9.9 (permanently
rejected, id 2525): instead of splitting the flat
alarmSnoozeOptionLabel string into two differently-sized Text nodes
(which would make it vanish from the render tree the protected
dismiss-guard test locates via find.text), a SEPARATE small Text is
added alongside it. The original label stays a single, untouched Text
node, still inside the same FilledButton the guard taps.

Verified against the full ringing-screen test surface (34 tests
across 5 files, including the protected dismiss-guard file) -- all
green, dismiss-guard file reconfirmed byte-identical to main.

lib/pantallas/pantalla_alarma_sonando.dart

@@ -225,6 +225,25 @@ class _PantallaAlarmaSonandoState extends State<PantallaAlarmaSonando> {
                     tokens: tokens,
                   ),
                   const SizedBox(height: 22),
+                  // Audit 9.4 (t4 line 419): "Lunes, 3 de agosto" between
+                  // the pill and the hero time -- never rendered before.
+                  // Purely additive: a new sibling Text, touching neither
+                  // the pill above nor the hero time below.
+                  Text(
+                    fechaLargaConDiaSemana(
+                      Localizations.localeOf(context).toString(),
+                      DateTime.now(),
+                    ),
+                    textAlign: TextAlign.center,
+                    style: TextStyle(
+                      fontSize: 14,
+                      fontWeight: FontWeight.w600,
+                      color: Theme.of(
+                        context,
+                      ).colorScheme.onSurface.withValues(alpha: 0.6),
+                    ),
+                  ),
+                  const SizedBox(height: 6),
                   FittedBox(
                     fit: BoxFit.scaleDown,
                     child: Text(
@@ -689,6 +708,20 @@ class _FilaSnoozeFija extends StatelessWidget {
     final forma = RoundedRectangleBorder(
       borderRadius: BorderRadius.circular(tokens.radiusMd),
     );
+    // Audit 9.10 (t4 line 433): the prototype stacks a big NUMBER over a
+    // small "min · habitual" unit — the SAME text-splitting conflict as
+    // 9.9 (permanently rejected, Engram id 2525): this flat string is
+    // exactly what the protected dismiss-guard test locates via
+    // `find.text(l10n.alarmSnoozeOptionLabel(N))` in four places, and
+    // splitting it into two differently-styled Text nodes would make
+    // that flat value vanish from the render tree.
+    //
+    // Resolved differently here than 9.9: rather than splitting THIS
+    // string, an entirely SEPARATE small qualifier Text is added
+    // alongside it (only on the destacado tile) — the original flat
+    // label stays a single, untouched, unstyled-differently Text node,
+    // still the exact widget the guard finds and taps. This delivers
+    // the "habitual" qualifier without the conflict 9.9 hit.
     final etiqueta = Text(l10n.alarmSnoozeOptionLabel(minutos));
     return Expanded(
       flex: esDestacado ? 3 : 2,
@@ -703,7 +736,21 @@ class _FilaSnoozeFija extends StatelessWidget {
                     foregroundColor: tokens.deepViolet,
                     shape: forma,
                   ),
-                  child: etiqueta,
+                  child: Column(
+                    mainAxisAlignment: MainAxisAlignment.center,
+                    mainAxisSize: MainAxisSize.min,
+                    children: [
+                      etiqueta,
+                      Text(
+                        l10n.alarmSnoozeUsualLabel,
+                        style: TextStyle(
+                          fontSize: 11,
+                          fontWeight: FontWeight.w800,
+                          color: tokens.deepViolet.withValues(alpha: 0.75),
+                        ),
+                      ),
+                    ],
+                  ),
                 )
                 : OutlinedButton(
                   onPressed: () => onPosponer(minutos),