refactor: patch connection indicator with timestamp

Server patches the ConnectionIndicator element with a timestamp on
each heartbeat. Client-side JS checks every second if the timestamp
is stale (>20s) and toggles red/green accordingly.

This properly detects connection loss since the indicator will turn
red if no patches are received.

features/snakegame/pages/game.templ

@@ -32,12 +32,12 @@ templ GamePage(sg *snake.SnakeGame, mySlot int, messages []chat.Message, chatCfg
 	@layouts.Base("Snake") {
 		<main
 			class="snake-wrapper flex flex-col items-center gap-4 p-4"
-			data-signals={ `{"chatMsg":"","lastPing":0}` }
+			data-signals={ `{"chatMsg":""}` }
 			data-init={ fmt.Sprintf("@get('/snake/%s/events',{requestCancellation:'disabled'})", gameID) }
 			data-on:keydown__throttle.100ms={ keydownScript(gameID) }
 			tabindex="0"
 		>
-			@components.ConnectionIndicator()
+			@components.ConnectionIndicator(0)
 			@GameContent(sg, mySlot, messages, chatCfg, gameID)
 		</main>
 	}