feat(chat): share SwiftUI chat across macOS+iOS

apps/shared/ClawdisKit/Sources/ClawdisChatUI/ChatPayloadDecoding.swift

@@ -0,0 +1,9 @@
+import ClawdisKit
+import Foundation
+
+enum ChatPayloadDecoding {
+    static func decode<T: Decodable>(_ payload: AnyCodable, as _: T.Type = T.self) throws -> T {
+        let data = try JSONEncoder().encode(payload)
+        return try JSONDecoder().decode(T.self, from: data)
+    }
+}