refactor: patch entire game content instead of individual components

Extract GameContent from GamePage so the SSE handler can patch a single
element and let DOM morphing diff the changes, replacing the per-component
sendGameComponents helper.

features/c4game/pages/game.templ

@@ -17,21 +17,27 @@ templ GamePage(g *connect4.Game, myColor int, messages []chat.Message, chatCfg c
 			data-signals="{chatMsg: ''}"
 			data-init={ datastar.GetSSE("/games/%s/events", g.ID) }
 		>
-			@sharedcomponents.BackToLobby()
-			@sharedcomponents.StealthTitle("text-3xl font-bold")
-			@components.PlayerInfo(g, myColor)
-			@components.StatusBanner(g, myColor)
-			<div class="c4-game-area">
-				@components.Board(g, myColor)
-				@chatcomponents.Chat(messages, chatCfg)
-			</div>
-			if g.Status == connect4.StatusWaitingForPlayer {
-				@components.InviteLink(g.ID)
-			}
+			@GameContent(g, myColor, messages, chatCfg)
 		</main>
 	}
 }
 
+templ GameContent(g *connect4.Game, myColor int, messages []chat.Message, chatCfg chatcomponents.Config) {
+	<div id="game-content">
+		@sharedcomponents.BackToLobby()
+		@sharedcomponents.StealthTitle("text-3xl font-bold")
+		@components.PlayerInfo(g, myColor)
+		@components.StatusBanner(g, myColor)
+		<div class="c4-game-area">
+			@components.Board(g, myColor)
+			@chatcomponents.Chat(messages, chatCfg)
+		</div>
+		if g.Status == connect4.StatusWaitingForPlayer {
+			@components.InviteLink(g.ID)
+		}
+	</div>
+}
+
 templ JoinPage(gameID string) {
 	@layouts.Base("Connect 4 - Join") {
 		@sharedcomponents.GameJoinPrompt(