fix: Corregir force unwraps y mejorar seguridad del código

- ManhwaWebScraper.swift: Eliminar force unwrap en URL con guard let
- ManhwaWebScraperOptimized.swift: Eliminar 2 force unwraps en URLs
- StorageServiceOptimized.swift: Usar .first en lugar de subscript [0]
- ImageCache.swift: Usar .first en lugar de subscript [0]
- Agregar caso invalidURL a ScrapingError enum

Build exitoso para iOS 15.0+ (simulador y device)
IPA generado y listo para sideloading

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

ios-app/Assets.xcassets/AppIcon.appiconset/Contents.json

@@ -0,0 +1,113 @@
+{
+  "images" : [
+    {
+      "idiom" : "iphone",
+      "scale" : "2x",
+      "size" : "20x20"
+    },
+    {
+      "idiom" : "iphone",
+      "scale" : "3x",
+      "size" : "20x20"
+    },
+    {
+      "idiom" : "iphone",
+      "scale" : "2x",
+      "size" : "29x29"
+    },
+    {
+      "idiom" : "iphone",
+      "scale" : "3x",
+      "size" : "29x29"
+    },
+    {
+      "idiom" : "iphone",
+      "scale" : "2x",
+      "size" : "40x40"
+    },
+    {
+      "idiom" : "iphone",
+      "scale" : "3x",
+      "size" : "40x40"
+    },
+    {
+      "idiom" : "iphone",
+      "scale" : "2x",
+      "size" : "60x60"
+    },
+    {
+      "idiom" : "iphone",
+      "scale" : "3x",
+      "size" : "60x60"
+    },
+    {
+      "idiom" : "iphone",
+      "scale" : "2x",
+      "size" : "76x76"
+    },
+    {
+      "idiom" : "iphone",
+      "scale" : "3x",
+      "size" : "76x76"
+    },
+    {
+      "idiom" : "iphone",
+      "scale" : "2x",
+      "size" : "83.5x83.5"
+    },
+    {
+      "idiom" : "ipad",
+      "scale" : "1x",
+      "size" : "20x20"
+    },
+    {
+      "idiom" : "ipad",
+      "scale" : "2x",
+      "size" : "20x20"
+    },
+    {
+      "idiom" : "ipad",
+      "scale" : "1x",
+      "size" : "29x29"
+    },
+    {
+      "idiom" : "ipad",
+      "scale" : "2x",
+      "size" : "29x29"
+    },
+    {
+      "idiom" : "ipad",
+      "scale" : "1x",
+      "size" : "40x40"
+    },
+    {
+      "idiom" : "ipad",
+      "scale" : "2x",
+      "size" : "40x40"
+    },
+    {
+      "idiom" : "ipad",
+      "scale" : "1x",
+      "size" : "76x76"
+    },
+    {
+      "idiom" : "ipad",
+      "scale" : "2x",
+      "size" : "76x76"
+    },
+    {
+      "idiom" : "ipad",
+      "scale" : "2x",
+      "size" : "83.5x83.5"
+    },
+    {
+      "idiom" : "ios-marketing",
+      "scale" : "1x",
+      "size" : "1024x1024"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}