feat(apple): generate type-safe L10n accessors and migrate all key literals

Replaces every stringly-typed localization key in the Apple app with
compile-time-checked accessors generated from localization/strings.json.
A mistyped key is now a build error instead of a silent fallback to the
raw key at runtime. The runtime path is unchanged: plain keys are
String.LocalizationValue constants resolved with String(localized:) and
Apple's String Catalog still does the lookup; keys with arguments become
typed, named functions applying args through String(format:).

Generator: new renderSwiftAccessors emits apple/VniDrop/Generated/L10n.swift,
wired into generate. Renamed generic arg1/arg2 tokens on four keys to
semantic names (receiver, transferName, deviceId) and updated their context
notes; positional output is unchanged so .xcstrings (bar the 4 comments)
and the Android XML regenerate identical.

Migration: every key-carrying value flipped to String.LocalizationValue
end to end, resolved only at the leaf. Zero key literals and zero
LocalizedStringKey remain in app or test code. macOS build passes; iOS
test run pending.

apple/VniDrop/UI/Feedback/UiMessage.swift

@@ -4,14 +4,14 @@ import Combine
 /// A localizable UI string: either a catalog key or dynamic text, ported from
 /// `UiText` in `ui/feedback/UiMessageController.kt`.
 enum UiText: Equatable {
-	case resource(String)   // Localizable.xcstrings key
+	case resource(String.LocalizationValue)   // Localizable.xcstrings key (use L10n.*)
 	case dynamic(String)
 
 	/// Resolves to display text. Keys go through the string catalog.
 	func resolved() -> String {
 		switch self {
 		case .dynamic(let value): return value
-		case .resource(let key): return String(localized: String.LocalizationValue(key))
+		case .resource(let value): return String(localized: value)
 		}
 	}
 }