feat: fix encoding for Windows tasklist output in IsWindowTitleActive()

[Copilot]

Windows tasklist command outputs text in the system's default codepage (typically GBK for Chinese systems), but Go reads it as UTF-8, causing garbled text that breaks string comparison with window titles.

Changes

• Decode tasklist output from GBK to UTF-8 using golang.org/x/text/encoding/simplifiedchinese
• Add fallback to raw output if decoding fails

// Before: garbled Chinese characters cause string match to fail
output := out.String()

// After: properly decoded output
decoder := simplifiedchinese.GBK.NewDecoder()
reader := transform.NewReader(&out, decoder)
decoded, err := io.ReadAll(reader)
if err != nil {
    decoded = out.Bytes()
}
output := string(decoded)

This allows the function to correctly match window titles containing non-ASCII characters.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[bug] wrong encoding for IsWindowTitleActive() output</issue_title>
<issue_description>```go
func IsWindowTitleActive(name string) (bool, error) {
name = getMappedName(name)
windowName := fmt.Sprintf("%s.bat - %s", name, getShortcut())

// Use tasklist to check if a window with the specific title exists
cmd := exec.Command("tasklist", "/V", "/FI", fmt.Sprintf("WINDOWTITLE eq %s", windowName))
var out bytes.Buffer
cmd.Stdout = &out
err := cmd.Run()
if err != nil {
return false, err
}

output := out.String()
// Check if cmd.exe process with the window title exists
// If window title is found, output will contain "cmd.exe" and the window title
res := strings.Contains(output, "cmd.exe") && strings.Contains(output, windowName)
return res, nil
}

in above code, output is wrong encoding, it's:

ӳ������ PID �Ự�� �Ự# �ڴ�ʹ�� ״̬ �û��� CPU ʱ�� ���ڱ���
========================= ======== ================ =========== ============ =============== ================================================== ============ ========================================================================
cmd.exe 10872 RDP-Tcp#0 1 4,912 K Running MACHINE\Administrator 0:00:00 casibase.bat - ���ݷ�ʽ

but windowName var is correct encoding, so the contains func return false wrongly.

need to fix encoding</issue_description>

## Comments on the Issue (you are @copilot in this section)

<comments>
</comments>

• Fixes [bug] wrong encoding for IsWindowTitleActive() output #131

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