Replace empty catch blocks with explicit exception handling in TarArchive validation methods

[Copilot]

Addresses code review feedback about empty catch blocks in TarArchive.Factory.cs. The IsTarFile and IsTarFileAsync methods use catch-all exception handling to detect invalid tar files, but the empty catch blocks obscured intent.

Changes

• Replace catch { } with explicit catch (Exception) in both validation methods
• Add comments explaining that all exceptions during header parsing indicate an invalid tar file

catch (Exception)
{
    // Catch all exceptions during tar header reading to determine if this is a valid tar file
    // Invalid tar files or corrupted streams will throw various exceptions
    return false;
}

The behavior is unchanged—these methods probe streams and return false for any exception rather than propagating to callers.

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