add Player model

Sources/stella/Decoders/MsgPack.swift

@@ -0,0 +1,18 @@
+import SwiftMsgpack
+import Vapor
+
+extension MsgPackEncoder: @retroactive ContentEncoder, @retroactive @unchecked Sendable {
+    public func encode<E>(_ encodable: E, to body: inout ByteBuffer, headers: inout HTTPHeaders) throws where E : Encodable {
+        let data = try self.encode(encodable)
+        body.writeString(data.base64EncodedString())
+    }
+}
+
+extension MsgPackDecoder: @retroactive ContentDecoder, @retroactive @unchecked Sendable {
+    public func decode<D>(_ decodable: D.Type, from body: ByteBuffer, headers: HTTPHeaders) throws -> D where D : Decodable {
+        guard let base64String = body.peekString(length: body.capacity), let data = Data(base64Encoded: base64String) else {
+            throw Abort(.badRequest)
+        }
+        return try self.decode(decodable, from: data)
+    }
+}