Add installation effects and draggable progress bar

Introduces animated installation effects overlay and makes the progress bar draggable. Adds maximize window support, improves window controls styling, and enforces a single app instance. Removes the unused Skins page and related translations. Refines  various UI details for a more polished user experience.

GUI/locales/en.json

@@ -4,14 +4,12 @@
     "mods": "Mods",
     "news": "News",
     "chat": "Players Chat",
-    "settings": "Settings",
-    "skins": "Skins"
+    "settings": "Settings"
   },
   "header": {
     "playersLabel": "Players:",
     "manageProfiles": "Manage Profiles",
-    "defaultProfile": "Default",
-    "f2p": "FREE TO PLAY"
+    "defaultProfile": "Default"
   },
   "install": {
     "title": "FREE TO PLAY LAUNCHER",
@@ -148,10 +146,6 @@
     "notificationText": "Join our Discord community!",
     "joinButton": "Join Discord"
   },
-  "skins": {
-    "title": "Skins",
-    "comingSoon": "Skin customization coming soon..."
-  },
   "common": {
     "confirm": "Confirm",
     "cancel": "Cancel",

GUI/locales/es.json

@@ -4,14 +4,12 @@
     "mods": "Mods",
     "news": "Noticias",
     "chat": "Chat de Jugadores",
-    "settings": "Configuración",
-    "skins": "Aspectos"
+    "settings": "Configuración"
   },
   "header": {
     "playersLabel": "Jugadores:",
     "manageProfiles": "Gestionar Perfiles",
-    "defaultProfile": "Predeterminado",
-    "f2p": "FREE TO PLAY"
+    "defaultProfile": "Predeterminado"
   },
   "install": {
     "title": "LAUNCHER GRATUITO",
@@ -148,10 +146,6 @@
     "notificationText": "¡Únete a nuestra comunidad de Discord!",
     "joinButton": "Unirse a Discord"
   },
-  "skins": {
-    "title": "Aspectos",
-    "comingSoon": "Personalización de aspectos próximamente..."
-  },
   "common": {
     "confirm": "Confirmar",
     "cancel": "Cancelar",

GUI/locales/pt-BR.json

@@ -4,14 +4,12 @@
     "mods": "Mods",
     "news": "Notícias",
     "chat": "Chat de Jogadores",
-    "settings": "Configurações",
-    "skins": "Aparências"
+    "settings": "Configurações"
   },
   "header": {
     "playersLabel": "Jogadores:",
     "manageProfiles": "Gerenciar Perfis",
-    "defaultProfile": "Padrão",
-    "f2p": "FREE TO PLAY"
+    "defaultProfile": "Padrão"
   },
   "install": {
     "title": "LANÇADOR JOGO GRATUITO",
@@ -148,10 +146,7 @@
     "notificationText": "Junte-se à nossa comunidade do Discord!",
     "joinButton": "Entrar no Discord"
   },
-  "skins": {
-    "title": "Aparências",
-    "comingSoon": "Personalização de aparências em breve..."
-  },
+
   "common": {
     "confirm": "Confirmar",
     "cancel": "Cancelar",