chore: gitignore generated _templ.go files, track .templ sources

Generated _templ.go files are deterministic output from .templ sources,
same as output.css from input.css. Remove them from version control to
reduce diff noise and merge conflicts. Add build:templ and live:templ
tasks to the Taskfile so generation happens as part of the build.

features/snakegame/components/chat.templ

@@ -0,0 +1,66 @@
+package components
+
+import (
+	"fmt"
+
+	"github.com/ryanhamamura/c4/snake"
+	"github.com/starfederation/datastar-go/datastar"
+)
+
+type ChatMessage struct {
+	Nickname string `json:"nickname"`
+	Slot     int    `json:"slot"`
+	Message  string `json:"message"`
+	Time     int64  `json:"time"`
+}
+
+templ Chat(messages []ChatMessage, gameID string) {
+	<div id="snake-chat" class="snake-chat">
+		<div class="snake-chat-history">
+			for _, m := range messages {
+				<div class="snake-chat-msg">
+					<span style={ fmt.Sprintf("color:%s;font-weight:bold;", chatColor(m.Slot)) }>
+						{ m.Nickname + ": " }
+					</span>
+					<span>{ m.Message }</span>
+				</div>
+			}
+		</div>
+		<div class="snake-chat-input" data-morph-ignore>
+			<input
+				type="text"
+				placeholder="Chat..."
+				autocomplete="off"
+				data-bind="chatMsg"
+				data-on:keydown.stop=""
+				data-on:keydown.key_enter={ datastar.PostSSE("/snake/%s/chat", gameID) }
+			/>
+			<button
+				type="button"
+				data-on:click={ datastar.PostSSE("/snake/%s/chat", gameID) }
+			>
+				Send
+			</button>
+		</div>
+		@chatAutoScroll()
+	</div>
+}
+
+templ chatAutoScroll() {
+	<script>
+	(function(){
+		var el = document.querySelector('.snake-chat-history');
+		if (!el) return;
+		el.scrollTop = el.scrollHeight;
+		new MutationObserver(function(){ el.scrollTop = el.scrollHeight; })
+			.observe(el, {childList:true, subtree:true});
+	})();
+	</script>
+}
+
+func chatColor(slot int) string {
+	if slot >= 0 && slot < len(snake.SnakeColors) {
+		return snake.SnakeColors[slot]
+	}
+	return "#666"
+}