Initial commit: Go driver for the Lian Li Galahad II LCD

Streams H.264 to the Galahad II LCD via USB (gousb) with:
- ffmpeg CLI transcoding (no fragile FFmpeg C-ABI bindings)
- pure-Go Annex-B access-unit splitting
- framerate pacing with graceful shutdown and USB reconnect
- TOML config, cobra CLI, structured slog logging, unit tests

internal/cli/daemon.go

@@ -0,0 +1,106 @@
+package cli
+
+import (
+	"errors"
+	"fmt"
+	"log/slog"
+	"time"
+
+	"github.com/spf13/cobra"
+
+	"galahad2lcd/internal/config"
+	"galahad2lcd/internal/device"
+	"galahad2lcd/internal/stream"
+	"galahad2lcd/internal/transcoder"
+)
+
+// openTimeout bounds how long the daemon waits for the USB device to appear.
+const openTimeout = 30 * time.Second
+
+func newDaemonCmd() *cobra.Command {
+	var (
+		configPath string
+		input      string
+		rotate     int
+		speed      float64
+		fps        float64
+	)
+
+	cmd := &cobra.Command{
+		Use:   "daemon",
+		Short: "Run the display streaming daemon",
+		Args:  cobra.NoArgs,
+		RunE: func(cmd *cobra.Command, _ []string) error {
+			cfg, err := config.Load(configPath)
+			if err != nil {
+				return err
+			}
+			if err := applyOverrides(cmd, &cfg, input, rotate, speed, fps); err != nil {
+				return err
+			}
+			if err := cfg.Validate(); err != nil {
+				return fmt.Errorf("invalid configuration: %w", err)
+			}
+			return runDaemon(cfg)
+		},
+	}
+
+	cmd.Flags().StringVar(&configPath, "config", config.DefaultConfigPath, "path to the configuration file")
+	cmd.Flags().StringVar(&input, "input", "", "override the input media file")
+	cmd.Flags().IntVar(&rotate, "rotate", 0, "override the rotation in degrees (0, 90, 180, 270)")
+	cmd.Flags().Float64Var(&speed, "speed", 0, "override the playback speed (>1 slower, <1 faster)")
+	cmd.Flags().Float64Var(&fps, "fps", 0, "override the output framerate (0 = auto)")
+	return cmd
+}
+
+// runDaemon transcodes the configured media, loads the resulting frames and
+// streams them to the display, reconnecting automatically if the USB link is
+// lost (e.g. after system suspend).
+func runDaemon(cfg config.Config) error {
+	ctx, stop := newSignalContext()
+	defer stop()
+
+	tc, err := transcoder.New()
+	if err != nil {
+		return err
+	}
+
+	slog.Info("transcoding input to H.264", "input", cfg.Display.Input, "rotate", cfg.Display.Rotate)
+	fps, err := tc.Transcode(ctx, cfg)
+	if err != nil {
+		return err
+	}
+	slog.Info("transcoding complete", "fps", fps, "cache", cfg.Stream.CachePath)
+
+	packets, err := stream.LoadPackets(cfg.Stream.CachePath)
+	if err != nil {
+		return err
+	}
+	if len(packets) == 0 {
+		return errors.New("no video frames found in input")
+	}
+	slog.Info("frames buffered", "count", len(packets))
+
+	dev, err := device.OpenWithRetry(ctx, cfg.USB.VendorID, cfg.USB.ProductID, openTimeout)
+	if err != nil {
+		return err
+	}
+	slog.Info("device connected")
+
+	for {
+		err := stream.New(dev, packets, fps, cfg.Display.Speed).Run(ctx)
+		if err == nil || ctx.Err() != nil {
+			_ = dev.Close()
+			return nil // clean shutdown
+		}
+
+		slog.Error("stream interrupted; reconnecting", "error", err)
+		_ = dev.Close()
+
+		dev, err = device.OpenWithRetry(ctx, cfg.USB.VendorID, cfg.USB.ProductID, openTimeout)
+		if err != nil {
+			return err
+		}
+		slog.Info("device reconnected")
+	}
+}