feature: init kotlin compose multiplatforme

backend/src/main/kotlin/eventDemo/sharedKernel/GetUserIdCredentials.kt

@@ -0,0 +1,13 @@
+package eventDemo.sharedKernel
+
+import eventDemo.shared.ids.UserId
+import io.ktor.server.application.ApplicationCall
+import io.ktor.server.auth.jwt.JWTPrincipal
+import io.ktor.server.auth.principal
+import kotlin.uuid.Uuid
+
+internal val ApplicationCall.currentUserId: UserId
+  get() =
+    principal<JWTPrincipal>()!!.run {
+      UserId(Uuid.parse(payload.getClaim("userid").asString()))
+    }