feat: add hello and time demo hub scripts

scripts/hello.hub.kts

@@ -0,0 +1,17 @@
+import java.time.LocalDateTime
+
+// @desc: Demo greeting API
+// @param: name | default=world | desc=Name to greet
+// @param: upper | default=false | desc=Uppercase output
+
+val args: Array<String> = emptyArray()
+val kv = args.mapNotNull {
+    val idx = it.indexOf('=')
+    if (idx <= 0) null else it.substring(0, idx) to it.substring(idx + 1)
+}.toMap()
+
+val name = kv["name"] ?: "world"
+val upper = (kv["upper"] ?: "false").toBoolean()
+val message = "Hello, $name @ ${LocalDateTime.now()}"
+
+println(if (upper) message.uppercase() else message)