refactor: patch entire game content for snake SSE handler

Same approach as connect4 — extract GameContent component and patch it
as a single element, letting DOM morphing handle the diff.

features/snakegame/pages/game.templ

@@ -37,29 +37,35 @@ templ GamePage(sg *snake.SnakeGame, mySlot int, messages []chat.Message, chatCfg
 			data-on:keydown.throttle_100ms={ keydownScript(gameID) }
 			tabindex="0"
 		>
-			@components.BackToLobby()
-			<h1 class="text-3xl font-bold">~~~~</h1>
-			@snakecomponents.PlayerList(sg, mySlot)
-			@snakecomponents.StatusBanner(sg, mySlot, gameID)
-			if sg.Status == snake.StatusInProgress || sg.Status == snake.StatusFinished {
-				if sg.Mode == snake.ModeMultiplayer {
-					<div class="snake-game-area">
-						@snakecomponents.Board(sg)
-						@chatcomponents.Chat(messages, chatCfg)
-					</div>
-				} else {
-					@snakecomponents.Board(sg)
-				}
-			} else if sg.Mode == snake.ModeMultiplayer {
-				@chatcomponents.Chat(messages, chatCfg)
-			}
-			if sg.Mode == snake.ModeMultiplayer && (sg.Status == snake.StatusWaitingForPlayers || sg.Status == snake.StatusCountdown) {
-				@snakecomponents.InviteLink(gameID)
-			}
+			@GameContent(sg, mySlot, messages, chatCfg, gameID)
 		</main>
 	}
 }
 
+templ GameContent(sg *snake.SnakeGame, mySlot int, messages []chat.Message, chatCfg chatcomponents.Config, gameID string) {
+	<div id="game-content">
+		@components.BackToLobby()
+		<h1 class="text-3xl font-bold">~~~~</h1>
+		@snakecomponents.PlayerList(sg, mySlot)
+		@snakecomponents.StatusBanner(sg, mySlot, gameID)
+		if sg.Status == snake.StatusInProgress || sg.Status == snake.StatusFinished {
+			if sg.Mode == snake.ModeMultiplayer {
+				<div class="snake-game-area">
+					@snakecomponents.Board(sg)
+					@chatcomponents.Chat(messages, chatCfg)
+				</div>
+			} else {
+				@snakecomponents.Board(sg)
+			}
+		} else if sg.Mode == snake.ModeMultiplayer {
+			@chatcomponents.Chat(messages, chatCfg)
+		}
+		if sg.Mode == snake.ModeMultiplayer && (sg.Status == snake.StatusWaitingForPlayers || sg.Status == snake.StatusCountdown) {
+			@snakecomponents.InviteLink(gameID)
+		}
+	</div>
+}
+
 templ JoinPage(gameID string) {
 	@layouts.Base("Snake - Join") {
 		@components.GameJoinPrompt(