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/task/task.go

@@ -0,0 +1,45 @@
+package task
+
+import (
+	"ffmpeg-gui/internal/ffmpeg"
+	"time"
+)
+
+// Type represents the type of a task.
+type Type string
+
+const (
+	TypeRemux  Type = "remux"
+	TypeEncode Type = "encode"
+	TypeBurn   Type = "burn_subtitle"
+)
+
+// Status represents the current state of a task.
+type Status string
+
+const (
+	StatusPending  Status = "pending"
+	StatusRunning  Status = "running"
+	StatusDone     Status = "done"
+	StatusFailed   Status = "failed"
+	StatusCanceled Status = "canceled"
+)
+
+// Task represents a single ffmpeg job.
+type Task struct {
+	ID          string                  `json:"id"`
+	Type        Type                    `json:"type"`
+	InputFile   string                  `json:"inputFile"`
+	OutputFile  string                  `json:"outputFile"`
+	Status      Status                  `json:"status"`
+	Progress    ffmpeg.Progress         `json:"progress"`
+	Encode      ffmpeg.EncodeSettings   `json:"encode,omitempty"`
+	Remux       ffmpeg.RemuxSettings    `json:"remux,omitempty"`
+	Subtitle    ffmpeg.SubtitleSettings `json:"subtitle,omitempty"`
+	Args        []string                `json:"-"`
+	Logs        []string                `json:"-"`
+	Error       string                  `json:"error,omitempty"`
+	CreatedAt   time.Time               `json:"createdAt"`
+	CompletedAt *time.Time              `json:"completedAt,omitempty"`
+	Cancel      func()                  `json:"-"`
+}