fix: resolve all linting errors and add SSE compression

- Add brotli compression (level 5) to long-lived SSE event streams
  (HandleGameEvents, HandleSnakeEvents) to reduce wire payload
- Fix all errcheck violations with nolint annotations for best-effort calls
- Fix goimports: separate stdlib, third-party, and local import groups
- Fix staticcheck: add package comments, use tagged switch
- Zero lint issues remaining

features/snakegame/handlers.go

@@ -9,11 +9,12 @@ import (
 	"github.com/alexedwards/scs/v2"
 	"github.com/go-chi/chi/v5"
 	"github.com/nats-io/nats.go"
+	"github.com/starfederation/datastar-go/datastar"
+
 	"github.com/ryanhamamura/c4/features/snakegame/components"
 	"github.com/ryanhamamura/c4/features/snakegame/pages"
 	"github.com/ryanhamamura/c4/game"
 	"github.com/ryanhamamura/c4/snake"
-	"github.com/starfederation/datastar-go/datastar"
 )
 
 func getPlayerID(sessions *scs.SessionManager, r *http.Request) snake.PlayerID {
@@ -90,7 +91,9 @@ func HandleSnakeEvents(snakeStore *snake.SnakeStore, nc *nats.Conn, sessions *sc
 		playerID := getPlayerID(sessions, r)
 		mySlot := si.GetPlayerSlot(playerID)
 
-		sse := datastar.NewSSE(w, r)
+		sse := datastar.NewSSE(w, r, datastar.WithCompression(
+			datastar.WithBrotli(datastar.WithBrotliLevel(5)),
+		))
 
 		// Send initial render
 		sg := si.GetGame()
@@ -110,7 +113,7 @@ func HandleSnakeEvents(snakeStore *snake.SnakeStore, nc *nats.Conn, sessions *sc
 		if err != nil {
 			return
 		}
-		defer gameSub.Unsubscribe()
+		defer gameSub.Unsubscribe() //nolint:errcheck
 
 		// Chat subscription (multiplayer only)
 		var chatCh chan *nats.Msg
@@ -124,7 +127,7 @@ func HandleSnakeEvents(snakeStore *snake.SnakeStore, nc *nats.Conn, sessions *sc
 			if err != nil {
 				return
 			}
-			defer chatSub.Unsubscribe()
+			defer chatSub.Unsubscribe() //nolint:errcheck
 		}
 
 		ctx := r.Context()

features/snakegame/routes.go

@@ -1,9 +1,11 @@
+// Package snakegame handles snake game routes, SSE event streaming, and chat.
 package snakegame
 
 import (
 	"github.com/alexedwards/scs/v2"
 	"github.com/go-chi/chi/v5"
 	"github.com/nats-io/nats.go"
+
 	"github.com/ryanhamamura/c4/snake"
 )