feat(ui): refresh premium visual assets

assets/mockups/pluriwave-aaa-mockup.prompt.txt

@@ -0,0 +1,3 @@
+PluriWave AAA mockup generated with image_gen.
+Visual direction: midnight-ocean glass, teal/cyan audio waves, coral sunrise accents, warm gold broadcast particles, accessible high contrast, no purple-dominant palette.
+Launcher/app icon intentionally preserved.

lib/widgets/pluri_icon.dart

@@ -73,7 +73,7 @@ class PluriIcon extends StatelessWidget {
       PluriIconGlyph.home => 'assets/icons/pluri_home.png',
       PluriIconGlyph.search => 'assets/icons/pluri_search.png',
       PluriIconGlyph.favorites => 'assets/icons/pluri_favorites.png',
-      PluriIconGlyph.alarm => null,
+      PluriIconGlyph.alarm => 'assets/icons/pluri_alarm.png',
       PluriIconGlyph.player => 'assets/icons/pluri_player.png',
       PluriIconGlyph.settings => 'assets/icons/pluri_settings.png',
     };

lib/widgets/pluri_premium_widgets.dart

@@ -33,6 +33,34 @@ class PluriScreenHeader extends StatelessWidget {
         padding: const EdgeInsets.all(18),
         child: Stack(
           children: [
+            Positioned.fill(
+              child: ClipRRect(
+                borderRadius: BorderRadius.circular(t.radiusLg + 8),
+                child: Opacity(
+                  opacity: 0.24,
+                  child: Image.asset(
+                    'assets/images/aurora_wave_banner.png',
+                    fit: BoxFit.cover,
+                    errorBuilder: (_, __, ___) => const SizedBox.shrink(),
+                  ),
+                ),
+              ),
+            ),
+            Positioned.fill(
+              child: DecoratedBox(
+                decoration: BoxDecoration(
+                  borderRadius: BorderRadius.circular(t.radiusLg + 8),
+                  gradient: LinearGradient(
+                    begin: Alignment.centerLeft,
+                    end: Alignment.centerRight,
+                    colors: [
+                      Colors.black.withValues(alpha: 0.58),
+                      Colors.black.withValues(alpha: 0.18),
+                    ],
+                  ),
+                ),
+              ),
+            ),
             Positioned(
               right: -36,
               top: -42,

lib/widgets/pluri_wave_scaffold.dart

@@ -57,6 +57,18 @@ class PluriWaveScaffold extends StatelessWidget {
               bottom: 80,
               child: _AuroraOrb(size: 260, color: t.warmCoral.withValues(alpha: 0.10)),
             ),
+            Positioned.fill(
+              child: IgnorePointer(
+                child: Opacity(
+                  opacity: 0.055,
+                  child: Image.asset(
+                    'assets/images/noise_soft.png',
+                    fit: BoxFit.cover,
+                    errorBuilder: (_, __, ___) => const SizedBox.shrink(),
+                  ),
+                ),
+              ),
+            ),
             body,
           ],
         ),