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/c4game/handlers.go

@@ -16,6 +16,7 @@ import (
 	"github.com/ryanhamamura/games/connect4"
 	"github.com/ryanhamamura/games/db/repository"
 	"github.com/ryanhamamura/games/features/c4game/pages"
+	sharedcomponents "github.com/ryanhamamura/games/features/common/components"
 	"github.com/ryanhamamura/games/sessions"
 )
 
@@ -119,7 +120,7 @@ func HandleGameEvents(store *connect4.Store, nc *nats.Conn, sm *scs.SessionManag
 		}
 
 		sendPing := func() error {
-			return sse.PatchSignals([]byte(fmt.Sprintf(`{"lastPing":%d}`, time.Now().UnixMilli())))
+			return sse.PatchElementTempl(sharedcomponents.ConnectionIndicator(time.Now().UnixMilli()))
 		}
 
 		// Send initial render and ping

features/c4game/pages/game.templ

@@ -15,10 +15,10 @@ templ GamePage(g *connect4.Game, myColor int, messages []chat.Message, chatCfg c
 	@layouts.Base("Connect 4") {
 		<main
 			class="flex flex-col items-center gap-4 p-4"
-			data-signals="{chatMsg: '', lastPing: 0}"
+			data-signals="{chatMsg: ''}"
 			data-init={ fmt.Sprintf("@get('/games/%s/events',{requestCancellation:'disabled'})", g.ID) }
 		>
-			@sharedcomponents.ConnectionIndicator()
+			@sharedcomponents.ConnectionIndicator(0)
 			@GameContent(g, myColor, messages, chatCfg)
 		</main>
 	}