fix(ios): restrict authentication capabilities and validate bootstrap types

Require iOS 18.4 for explicit upload denial in the isolated authentication window. Add origin-bound generated download policy, app-switcher privacy, typed metadata regressions and original community icon assets. Seven portable tests and Swift formatting checks pass; Apple SDK validation remains external.

ios/Sources/Assets.xcassets/AppIcon.appiconset/Contents.json

@@ -0,0 +1,14 @@
+{
+  "images": [
+    {
+      "filename": "AppIcon.png",
+      "idiom": "universal",
+      "platform": "ios",
+      "size": "1024x1024"
+    }
+  ],
+  "info": {
+    "author": "Yuvomi Mobile contributors",
+    "version": 1
+  }
+}