feat: add chat emote system (/hi, /gg, /go, /wait, /help)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

game/emote.go

@@ -0,0 +1,17 @@
+package game
+
+var emotes = map[string]string{
+	"/hi":   "👋 waves hello!",
+	"/gg":   "🎉 says GG!",
+	"/go":   "⚔️ says Let's go!",
+	"/wait": "✋ says Wait!",
+	"/help": "🆘 calls for help!",
+}
+
+func ParseEmote(input string) (string, bool) {
+	if input == "" {
+		return "", false
+	}
+	text, ok := emotes[input]
+	return text, ok
+}