Simplify codebase and fix Enter key on home page

- Enter key now triggers createGame action on home page
- Remove redundant setNickname action from home page
- Remove unused code: join channel, Leave(), Stop() methods
- Consolidate ID generation into game.GenerateID()
- Remove unused CreatedAt field from Game struct

game/types.go

@@ -1,7 +1,5 @@
 package game
 
-import "time"
-
 type PlayerID string
 
 type Player struct {
@@ -27,7 +25,6 @@ type Game struct {
 	Status       GameStatus
 	Winner       *Player
 	WinningCells [][2]int // Coordinates of winning 4 cells for highlighting
-	CreatedAt    time.Time
 }
 
 func NewGame(id string) *Game {
@@ -36,6 +33,5 @@ func NewGame(id string) *Game {
 		Board:       [6][7]int{},
 		CurrentTurn: 1, // Red goes first
 		Status:      StatusWaitingForPlayer,
-		CreatedAt:   time.Now(),
 	}
 }