Auto-generate nicknames for invitees joining via link

Invitees no longer need to enter a nickname - they automatically
join with a random name like "Swift Tiger" or "Happy Falcon".
Game creators still enter their nickname manually.

game/store.go

@@ -50,6 +50,24 @@ func GenerateID(size int) string {
 	return hex.EncodeToString(b)
 }
 
+func GenerateNickname() string {
+	adjectives := []string{
+		"Swift", "Happy", "Clever", "Brave", "Mighty",
+		"Quick", "Calm", "Bold", "Lucky", "Wise",
+		"Eager", "Noble", "Keen", "Bright", "Vivid",
+	}
+	nouns := []string{
+		"Tiger", "Falcon", "Dragon", "Phoenix", "Wolf",
+		"Eagle", "Panda", "Otter", "Fox", "Bear",
+		"Hawk", "Lion", "Raven", "Shark", "Owl",
+	}
+	b := make([]byte, 2)
+	rand.Read(b)
+	adj := adjectives[int(b[0])%len(adjectives)]
+	noun := nouns[int(b[1])%len(nouns)]
+	return adj + " " + noun
+}
+
 type GameInstance struct {
 	game      *Game
 	gameMu    sync.RWMutex

main.go

@@ -106,16 +106,35 @@ func main() {
 			c.Sync()
 		})
 
-		// If nickname exists in session and game exists, join immediately
-		if gameExists && sessionNickname != "" && gi.GetPlayerColor(playerID) == 0 {
-			player := &game.Player{
-				ID:       playerID,
-				Nickname: sessionNickname,
+		// Auto-join logic
+		if gameExists && gi.GetPlayerColor(playerID) == 0 {
+			g := gi.GetGame()
+			// Invitee: game is waiting for second player - auto-generate nickname and join
+			if g.Status == game.StatusWaitingForPlayer {
+				name := sessionNickname
+				if name == "" {
+					name = game.GenerateNickname()
+					c.Session().Set("nickname", name)
+				}
+				player := &game.Player{
+					ID:       playerID,
+					Nickname: name,
+				}
+				gi.Join(&game.PlayerSession{
+					Player: player,
+					Sync:   c,
+				})
+			} else if sessionNickname != "" {
+				// Reconnecting player with existing nickname
+				player := &game.Player{
+					ID:       playerID,
+					Nickname: sessionNickname,
+				}
+				gi.Join(&game.PlayerSession{
+					Player: player,
+					Sync:   c,
+				})
 			}
-			gi.Join(&game.PlayerSession{
-				Player: player,
-				Sync:   c,
-			})
 		}
 
 		c.View(func() h.H {