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/authenticator/battlenet_restore_test.go

@@ -0,0 +1,66 @@
+package authenticator
+
+import (
+	"testing"
+)
+
+// TestRestoreCodeRoundTrip verifies that restoreCharToByte exactly
+// inverts restoreByteToChar across every 5-bit value the encoding
+// produces. A regression here would silently corrupt the HMAC key the
+// Restore flow sends to Blizzard, so the round-trip is the cheapest
+// possible safety net.
+func TestRestoreCodeRoundTrip(t *testing.T) {
+	for v := 0; v < 32; v++ {
+		c := restoreByteToChar(byte(v))
+		got, ok := restoreCharToByte(c)
+		if !ok {
+			t.Fatalf("v=%d encoded as %q but failed to decode", v, c)
+		}
+		if int(got) != v {
+			t.Fatalf("v=%d → %q → %d (want %d)", v, c, got, v)
+		}
+	}
+}
+
+// TestRestoreCharToByteRejectsAmbiguous confirms that the four letters
+// deliberately omitted from the Battle.Net restore alphabet (I, L, O,
+// S) are rejected on decode. A user typing "1" instead of "I" should
+// land on the "1" branch; "I" should be a hard error rather than a
+// silent misdecode.
+func TestRestoreCharToByteRejectsAmbiguous(t *testing.T) {
+	for _, c := range []byte{'I', 'L', 'O', 'S'} {
+		if _, ok := restoreCharToByte(c); ok {
+			t.Errorf("char %q must not decode", c)
+		}
+	}
+}
+
+// TestDecodeRestoreCodeLength sanity-checks the length validator.
+func TestDecodeRestoreCodeLength(t *testing.T) {
+	if _, err := decodeRestoreCode("ABCDEFGHI"); err == nil {
+		t.Error("expected error for 9-char input")
+	}
+	if _, err := decodeRestoreCode("ABCDEFGHIJK"); err == nil {
+		t.Error("expected error for 11-char input")
+	}
+	// 10 valid characters
+	if _, err := decodeRestoreCode("ABCDEFGHJK"); err != nil {
+		t.Errorf("unexpected error for 10-char input: %v", err)
+	}
+}
+
+// TestNormalizeBnetSerial verifies the user-friendly formats (dashes
+// and spaces, mixed case) all collapse to the protocol-required form.
+func TestNormalizeBnetSerial(t *testing.T) {
+	cases := map[string]string{
+		"us-1234-5678-9012":   "US123456789012",
+		"US-1234-5678-9012":   "US123456789012",
+		"  US 1234 5678 9012": "US123456789012",
+		"us123456789012":      "US123456789012",
+	}
+	for in, want := range cases {
+		if got := normalizeBnetSerial(in); got != want {
+			t.Errorf("normalizeBnetSerial(%q) = %q, want %q", in, got, want)
+		}
+	}
+}