fix: navbar hover gris (overlayColor) + soporte UI/UX mejorado + políticas en dialog

- Navbar: reemplaza hoverColor deprecated por IconButton.styleFrom(overlayColor)
- Support: rediseño completo con tarjetas, secciones y manejo correcto de URLs vacías
- Políticas/Términos: carga desde GET /settings/policies y muestra en dialog in-app

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/ui/shared/navbar.dart

@@ -39,8 +39,13 @@ class _NavbarState extends State<Navbar> {
     final iconColor = isDark ? Colors.white70 : const Color(0xFF475569);
     final bgColor = isDark ? const Color(0xFF1E293B) : Colors.white;
     final hoverColor = isDark
-        ? Colors.white.withOpacity(0.08)
-        : const Color(0xFF42A4EF).withOpacity(0.08);
+        ? Colors.white.withOpacity(0.10)
+        : const Color(0xFF42A4EF).withOpacity(0.10);
+    final overlayColor = WidgetStateProperty.resolveWith<Color?>((states) {
+      if (states.contains(WidgetState.hovered)) return hoverColor;
+      if (states.contains(WidgetState.pressed)) return hoverColor.withOpacity(0.2);
+      return Colors.transparent;
+    });
 
     final reputation = scoreProvider.reputation;
     final pendingCount =
@@ -63,7 +68,7 @@ class _NavbarState extends State<Navbar> {
           if (size.width <= 700)
             IconButton(
               icon: Icon(Icons.menu, color: iconColor, size: 22),
-              hoverColor: hoverColor,
+              style: IconButton.styleFrom(overlayColor: hoverColor),
               onPressed: SideMenuProvider.openMenu,
             ),
 
@@ -89,7 +94,7 @@ class _NavbarState extends State<Navbar> {
           // Toggle día/noche
           IconButton(
             tooltip: isDark ? 'Modo día' : 'Modo noche',
-            hoverColor: hoverColor,
+            style: IconButton.styleFrom(overlayColor: hoverColor),
             icon: Icon(
               isDark ? Icons.light_mode : Icons.dark_mode,
               color: isDark ? Colors.amber : iconColor,
@@ -104,7 +109,7 @@ class _NavbarState extends State<Navbar> {
             children: [
               IconButton(
                 tooltip: 'Notificaciones',
-                hoverColor: hoverColor,
+                style: IconButton.styleFrom(overlayColor: hoverColor),
                 icon: Icon(
                   pendingCount > 0
                       ? Icons.notifications_active