fix: use correct Datastar keydown event syntax

Replace invalid .key_enter and .enter modifiers with evt.key === 'Enter'
guard in the expression, per Datastar docs. Also fix __stop and __throttle
modifier syntax to use double underscores.

features/lobby/pages/lobby.templ

@@ -73,7 +73,7 @@ templ LobbyPage(data LobbyData) {
 							placeholder="Enter your nickname"
 							data-bind="nickname"
 							required
-							data-on:keydown.enter={ datastar.PostSSE("/games") }
+							data-on:keydown={ "evt.key === 'Enter' && " + datastar.PostSSE("/games") }
 						/>
 					</fieldset>
 					<button