feat(apple): adopt Icon Composer app icon

Replace the legacy AppIcon.appiconset with an Icon Composer AppIcon.icon
bundle in the target's resources. ASSETCATALOG_COMPILER_APPICON_NAME already
points at "AppIcon"; the .icon back-deploys to the iOS 18.2 target.

apple/VniDrop/Resources/AppIcon.icon/icon.json

@@ -0,0 +1,65 @@
+{
+  "features" : [
+    "refractivity"
+  ],
+  "fill" : {
+    "linear-gradient" : [
+      "extended-gray:1.00000,1.00000",
+      "display-p3:0.55433,0.59923,0.92884,1.00000"
+    ]
+  },
+  "groups" : [
+    {
+      "blend-mode" : "normal",
+      "blur-material" : null,
+      "layers" : [
+        {
+          "image-name" : "Mask.svg",
+          "name" : "Mask"
+        }
+      ],
+      "lighting" : "individual",
+      "refractivity" : {
+        "depth" : 0.5,
+        "enabled" : true,
+        "strength" : 0
+      },
+      "shadow" : {
+        "kind" : "neutral",
+        "opacity" : 0.6
+      },
+      "specular" : true,
+      "translucency" : {
+        "enabled" : true,
+        "value" : 0.8
+      }
+    },
+    {
+      "layers" : [
+        {
+          "image-name" : "Drop.svg",
+          "name" : "Drop"
+        },
+        {
+          "image-name" : "U.svg",
+          "name" : "U"
+        }
+      ],
+      "lighting" : "combined",
+      "shadow" : {
+        "kind" : "neutral",
+        "opacity" : 0.6
+      },
+      "translucency" : {
+        "enabled" : true,
+        "value" : 0.4
+      }
+    }
+  ],
+  "supported-platforms" : {
+    "circles" : [
+      "watchOS"
+    ],
+    "squares" : "shared"
+  }
+}