feat: FFmpeg GUI desktop application

Wails v2 + Vue3 + Go project with:
- Encode/Remux/Subtitle burn with hardware acceleration
- Real-time progress with ffmpeg stderr parsing (\r delimiter handling)
- Task queue with cancel support
- Per-task log viewer with color-coded output
- Custom frameless window with resize support
- Dark/light theme toggle
- Hardware encoder detection (NVENC/QSV/AMF)

internal/hwaccel/detect.go

@@ -0,0 +1,92 @@
+package hwaccel
+
+import (
+	"ffmpeg-gui/internal/ffmpeg"
+	"strings"
+)
+
+// HWEncoder represents a detected hardware encoder.
+type HWEncoder struct {
+	Name      string `json:"name"`  // e.g., "h264_nvenc"
+	Label     string `json:"label"` // e.g., "NVIDIA NVENC H.264"
+	Type      string `json:"type"`  // "nvidia", "intel", "amd", "software"
+	Codec     string `json:"codec"` // "h264", "hevc", "av1"
+	Available bool   `json:"available"`
+}
+
+// Accelerator represents a detected hardware acceleration method.
+type Accelerator struct {
+	Name      string `json:"name"`
+	Available bool   `json:"available"`
+}
+
+// Detector detects hardware acceleration capabilities.
+type Detector struct {
+	exec *ffmpeg.Executor
+}
+
+// NewDetector creates a new hardware detector.
+func NewDetector(exec *ffmpeg.Executor) *Detector {
+	return &Detector{exec: exec}
+}
+
+// knownEncoders defines all hardware encoders to check for.
+var knownEncoders = []struct {
+	Name  string
+	Type  string
+	Codec string
+	Label string
+}{
+	// NVIDIA NVENC
+	{"h264_nvenc", "nvidia", "h264", "NVIDIA NVENC H.264"},
+	{"hevc_nvenc", "nvidia", "hevc", "NVIDIA NVENC H.265/HEVC"},
+	{"av1_nvenc", "nvidia", "av1", "NVIDIA NVENC AV1"},
+	// Intel QSV
+	{"h264_qsv", "intel", "h264", "Intel QSV H.264"},
+	{"hevc_qsv", "intel", "hevc", "Intel QSV H.265/HEVC"},
+	{"av1_qsv", "intel", "av1", "Intel QSV AV1"},
+	// AMD AMF
+	{"h264_amf", "amd", "h264", "AMD AMF H.264"},
+	{"hevc_amf", "amd", "hevc", "AMD AMF H.265/HEVC"},
+	{"av1_amf", "amd", "av1", "AMD AMF AV1"},
+}
+
+// DetectEncoders detects available hardware encoders.
+func (d *Detector) DetectEncoders() ([]HWEncoder, error) {
+	out, err := d.exec.RunSync("-encoders")
+	if err != nil {
+		return nil, err
+	}
+
+	var encoders []HWEncoder
+	for _, ke := range knownEncoders {
+		available := strings.Contains(out, ke.Name)
+		encoders = append(encoders, HWEncoder{
+			Name:      ke.Name,
+			Label:     ke.Label,
+			Type:      ke.Type,
+			Codec:     ke.Codec,
+			Available: available,
+		})
+	}
+	return encoders, nil
+}
+
+// DetectAccelerators detects available hardware acceleration methods.
+func (d *Detector) DetectAccelerators() ([]Accelerator, error) {
+	out, err := d.exec.RunSync("-hwaccels")
+	if err != nil {
+		return nil, err
+	}
+
+	known := []string{"cuda", "d3d11va", "dxva2", "qsv", "vulkan"}
+
+	var accels []Accelerator
+	for _, k := range known {
+		accels = append(accels, Accelerator{
+			Name:      k,
+			Available: strings.Contains(out, k),
+		})
+	}
+	return accels, nil
+}