refactor: remove persister abstraction layer

Inline persistence logic directly into game stores and handlers:
- game/persist.go: DB mapping methods on GameStore and GameInstance
- snake/persist.go: DB mapping methods on SnakeStore and SnakeGameInstance
- Chat persistence inlined into c4game handlers
- Delete db/persister.go (GamePersister, SnakePersister, ChatPersister)
- Stores now take *repository.Queries directly instead of Persister interface

router/router.go

@@ -8,7 +8,6 @@ import (
 	"sync"
 
 	"github.com/ryanhamamura/c4/config"
-	"github.com/ryanhamamura/c4/db"
 	"github.com/ryanhamamura/c4/db/repository"
 	"github.com/ryanhamamura/c4/features/auth"
 	"github.com/ryanhamamura/c4/features/c4game"
@@ -30,7 +29,6 @@ func SetupRoutes(
 	nc *nats.Conn,
 	store *game.GameStore,
 	snakeStore *snake.SnakeStore,
-	chatPersister *db.ChatPersister,
 	assets embed.FS,
 ) error {
 	// Static assets
@@ -44,7 +42,7 @@ func SetupRoutes(
 
 	auth.SetupRoutes(router, queries, sessions)
 	lobby.SetupRoutes(router, queries, sessions, store, snakeStore)
-	c4game.SetupRoutes(router, store, nc, sessions, chatPersister)
+	c4game.SetupRoutes(router, store, nc, sessions, queries)
 	snakegame.SetupRoutes(router, snakeStore, nc, sessions)
 
 	return nil