fix: resolve wastedassign lint warnings in channel subpackages

Remove wasted initial assignments before switch statements in
onebot (segType), telegram (filename), and wecom (mediaType).

cmd/picoclaw/internal/gateway/helpers.go

@@ -192,7 +192,7 @@ func gatewayCmd(debug bool) error {
 	msgBus.Close()
 
 	// Use a fresh context with timeout for graceful shutdown,
-	// since the original ctx is already cancelled.
+	// since the original ctx is already canceled.
 	shutdownCtx, shutdownCancel := context.WithTimeout(context.Background(), 15*time.Second)
 	defer shutdownCancel()
 

pkg/bus/bus_test.go

@@ -73,13 +73,13 @@ func TestPublishInbound_ContextCancel(t *testing.T) {
 		}
 	}
 
-	// Now buffer is full; publish with a cancelled context
+	// Now buffer is full; publish with a canceled context
 	cancelCtx, cancel := context.WithCancel(context.Background())
 	cancel()
 
 	err := mb.PublishInbound(cancelCtx, InboundMessage{Content: "overflow"})
 	if err == nil {
-		t.Fatal("expected error from cancelled context, got nil")
+		t.Fatal("expected error from canceled context, got nil")
 	}
 	if err != context.Canceled {
 		t.Fatalf("expected context.Canceled, got %v", err)
@@ -115,7 +115,7 @@ func TestConsumeInbound_ContextCancel(t *testing.T) {
 
 	_, ok := mb.ConsumeInbound(ctx)
 	if ok {
-		t.Fatal("expected ok=false when context is cancelled")
+		t.Fatal("expected ok=false when context is canceled")
 	}
 }
 

pkg/channels/manager.go

@@ -455,7 +455,7 @@ func (m *Manager) runWorker(ctx context.Context, name string, w *channelWorker)
 func (m *Manager) sendWithRetry(ctx context.Context, name string, w *channelWorker, msg bus.OutboundMessage) {
 	// Rate limit: wait for token
 	if err := w.limiter.Wait(ctx); err != nil {
-		// ctx cancelled, shutting down
+		// ctx canceled, shutting down
 		return
 	}
 

pkg/channels/manager_test.go

@@ -245,7 +245,7 @@ func TestSendWithRetry_ContextCancelled(t *testing.T) {
 
 	m.sendWithRetry(ctx, "test", w, msg)
 
-	// Should have called Send once, then noticed ctx cancelled during backoff
+	// Should have called Send once, then noticed ctx canceled during backoff
 	if callCount != 1 {
 		t.Fatalf("expected 1 Send call before context cancellation, got %d", callCount)
 	}

pkg/channels/onebot/onebot.go

@@ -469,7 +469,7 @@ func (c *OneBotChannel) SendMedia(ctx context.Context, msg bus.OutboundMediaMess
 			continue
 		}
 
-		segType := "image"
+		var segType string
 		switch part.Type {
 		case "image":
 			segType = "image"

pkg/channels/telegram/telegram.go

@@ -243,11 +243,6 @@ func (c *TelegramChannel) SendMedia(ctx context.Context, msg bus.OutboundMediaMe
 			continue
 		}
 
-		filename := part.Filename
-		if filename == "" {
-			filename = "file"
-		}
-
 		switch part.Type {
 		case "image":
 			params := &telego.SendPhotoParams{

pkg/channels/wecom/app.go

@@ -221,7 +221,7 @@ func (c *WeComAppChannel) SendMedia(ctx context.Context, msg bus.OutboundMediaMe
 		}
 
 		// Map part type to WeCom media type
-		mediaType := "file"
+		var mediaType string
 		switch part.Type {
 		case "image":
 			mediaType = "image"