feat: Phase 1 WinAuth Go 移植完整实现

将原 C#/.NET WinAuth 移植为 Go + Gio GUI，覆盖 Phase 1 全部功能。

核心模块：
- internal/authenticator: TOTP (Google/Microsoft/Okta) + HOTP + BattleNet + Steam，含
  enroll/sync/code 生成、Steam 交易确认轮询
- internal/config: YAML 配置 + 老版 WinAuth XML 导入（DPAPI + Password + Blowfish/PBKDF2 解密链）
- internal/crypto: 现代加密 (WAGO1) + DPAPI 跨平台封装 + 老版 Blowfish ECB
- internal/win32: 单实例 Mutex 锁 + 全局热键管理器 (RegisterHotKey + PeekMessage 泵) +
  SendInput Unicode 注入 + 剪贴板文本/CF_DIB 图像读写 + AttachThreadInput 焦点切换
- internal/hotkey: "Ctrl+Alt+G" 风格快捷键字符串解析/格式化
- internal/qr: gozxing 二维码解码 + otpauth:// URI 解析
- internal/i18n: en/zh-CN/de 三语 TOML

UI 模块 (Gio)：
- 主窗口：圆环倒计时进度条、复制按钮 + Toast 反馈、空列表占位、行分隔线
- 添加流程：vendor 菜单 + 各 vendor 独立对话框 + 二维码扫描入口（文件 / 剪贴板）
- 设置：密码加密、老版 XML 导入、每条目热键配置
- Steam：注册向导（含 captcha/email/SMS 多步）+ 交易确认窗

构建：Windows 主目标，非 Windows 平台所有 Win32 功能走 build-tag 桩实现。

internal/ui/progress_ring.go

@@ -0,0 +1,80 @@
+package ui
+
+import (
+	"image"
+	"image/color"
+	"math"
+
+	"gioui.org/f32"
+	"gioui.org/layout"
+	"gioui.org/op/clip"
+	"gioui.org/op/paint"
+	"gioui.org/unit"
+)
+
+// progressRing renders a circular progress indicator. Progress is clamped
+// to [0, 1]; 1.0 fills the full circle. Drawing approximates the arc with
+// short line segments, which is plenty smooth at the small sizes used in
+// list rows.
+type progressRing struct {
+	Size     unit.Dp
+	Stroke   unit.Dp
+	Progress float32
+	Color    color.NRGBA
+	BgColor  color.NRGBA
+}
+
+func (r progressRing) Layout(gtx layout.Context) layout.Dimensions {
+	sizePx := gtx.Dp(r.Size)
+	if sizePx <= 0 {
+		return layout.Dimensions{}
+	}
+	strokePx := float32(gtx.Dp(r.Stroke))
+	if strokePx <= 0 {
+		strokePx = 2
+	}
+	center := f32.Pt(float32(sizePx)/2, float32(sizePx)/2)
+	radius := float32(sizePx)/2 - strokePx/2
+
+	if r.BgColor.A > 0 {
+		var bg clip.Path
+		bg.Begin(gtx.Ops)
+		buildArc(&bg, center, radius, -math.Pi/2, math.Pi*2)
+		paint.FillShape(gtx.Ops, r.BgColor,
+			clip.Stroke{Path: bg.End(), Width: strokePx}.Op())
+	}
+
+	if r.Progress > 0 {
+		sweep := float64(r.Progress) * math.Pi * 2
+		if sweep > math.Pi*2 {
+			sweep = math.Pi * 2
+		}
+		var fg clip.Path
+		fg.Begin(gtx.Ops)
+		buildArc(&fg, center, radius, -math.Pi/2, sweep)
+		paint.FillShape(gtx.Ops, r.Color,
+			clip.Stroke{Path: fg.End(), Width: strokePx}.Op())
+	}
+
+	return layout.Dimensions{Size: image.Pt(sizePx, sizePx)}
+}
+
+// buildArc emits a polyline approximation of an arc into p. startRad is
+// the starting angle (radians, 0 = +x axis, clockwise), sweepRad is the
+// signed angular extent.
+func buildArc(p *clip.Path, center f32.Point, radius float32, startRad, sweepRad float64) {
+	const segs = 48
+	step := sweepRad / float64(segs)
+	start := f32.Pt(
+		center.X+radius*float32(math.Cos(startRad)),
+		center.Y+radius*float32(math.Sin(startRad)),
+	)
+	p.MoveTo(start)
+	for i := 1; i <= segs; i++ {
+		a := startRad + step*float64(i)
+		p.LineTo(f32.Pt(
+			center.X+radius*float32(math.Cos(a)),
+			center.Y+radius*float32(math.Sin(a)),
+		))
+	}
+}