deps: update via to v0.15.0, remove vianats dependency

NATS is now built into via.New() automatically. Stores use the new
v.PubSub() accessor instead of the removed vianats package.

main.go

@@ -24,7 +24,6 @@ import (
 	"github.com/ryanhamamura/c4/ui"
 	"github.com/ryanhamamura/via"
 	"github.com/ryanhamamura/via/h"
-	"github.com/ryanhamamura/via/vianats"
 )
 
 var (
@@ -68,24 +67,18 @@ func main() {
 		log.Fatal(err)
 	}
 
-	ctx := context.Background()
-	ns, err := vianats.New(ctx, "./data/nats")
-	if err != nil {
-		log.Fatal(err)
-	}
-	store.SetPubSub(ns)
-	snakeStore.SetPubSub(ns)
-
 	v := via.New()
 	v.Config(via.Options{
 		LogLevel:       via.LogLevelDebug,
 		DocumentTitle:  "Game Lobby",
 		ServerAddress:  ":" + port(),
 		SessionManager: sessionManager,
-		PubSub:         ns,
 		Plugins:        []via.Plugin{DaisyUIPlugin},
 	})
 
+	store.SetPubSub(v.PubSub())
+	snakeStore.SetPubSub(v.PubSub())
+
 	// Home page - tabbed lobby
 	v.Page("/", func(c *via.Context) {
 		userID := c.Session().GetString("user_id")