Fix command line relative path resolution

[Copilot]

Command line arguments with relative paths (e.g., quicklook 1.txt) failed when invoked from directories other than the QuickLook installation directory. File.Exists() and Directory.Exists() were checking paths against the application's working directory instead of the shell's current directory.

Changes

• Convert relative paths to absolute using Path.GetFullPath() before existence checks in both first and second instance code paths
• Add specific exception handling for ArgumentException, SecurityException, NotSupportedException, and PathTooLongException

// Before
if (e.Args.Any() && (Directory.Exists(e.Args.First()) || File.Exists(e.Args.First())))
    PipeServerManager.SendMessage(PipeMessages.Toggle, e.Args.First());

// After
if (e.Args.Any())
{
    try
    {
        var path = Path.GetFullPath(e.Args.First());
        if (Directory.Exists(path) || File.Exists(path))
            PipeServerManager.SendMessage(PipeMessages.Toggle, path);
    }
    catch (Exception ex) when (ex is ArgumentException || ex is SecurityException || 
                               ex is NotSupportedException || ex is PathTooLongException)
    {
        // Invalid path, ignore
    }
}

Absolute paths continue to work unchanged. Invalid paths are silently ignored.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Command line only works with absolute path</issue_title>
<issue_description>Describe the bug

2026-01-13.214436.mp4

As the video shows:

• Using relative path quicklook 1.txt does nothing.
• Using absolute path quicklook D:/test/1.txt shows preview.
• When I change current dir to QuickLook program folder, these two ways both work.

To Reproduce
Follow my video.

Expected behavior
Relative path also works.

Desktop (please complete the following information):

• OS Version: Windows 11 PRO 25H2 26200.7462
• QuickLook Version: 4.4.0 from EXE installer
  </issue_description>

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

• Fixes Command line only works with absolute path #1856

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[Copilot]

Pull request overview

This PR fixes command line relative path resolution by converting relative paths to absolute paths before checking file/directory existence. Previously, quicklook 1.txt only worked when invoked from the QuickLook installation directory.

Changes:

• Added Path.GetFullPath() call to convert relative paths to absolute before existence checks
• Wrapped path resolution in try-catch blocks to handle invalid paths gracefully

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[Copilot]

The catch block is too broad and catches all exceptions. According to the PR description, specific exceptions should be caught: ArgumentException, SecurityException, NotSupportedException, and PathTooLongException. The current implementation could silently swallow unexpected exceptions that should be handled or logged differently. Consider using a filtered catch clause to only handle path-related exceptions.

[Copilot]

The control flow is incorrect. The duplicate message MessageBox will now always be shown, even when a valid file path is successfully processed. Previously, the else clause ensured the message was only shown when no arguments were provided or the path was invalid. This breaks the second instance behavior - when a user opens a file from a second instance, they will see both the file preview AND the duplicate instance message. The MessageBox call on lines 322-323 should only execute when args are empty or when the path is invalid/doesn't exist.

[Copilot]

The catch block is too broad and catches all exceptions. According to the PR description, specific exceptions should be caught: ArgumentException, SecurityException, NotSupportedException, and PathTooLongException. The current implementation could silently swallow unexpected exceptions that should be handled or logged differently. Consider using a filtered catch clause to only handle path-related exceptions.