Detect junctions and avoid traversing them

[brasky]

I believe this fixes #18

I was able to repro the issue with this PS script which also has some additional sanity check cases. I am no longer getting the access denied error with this build. I also tested perf against identical 126GB folders, and all was well (it was pretty fast)

# Set up
$testRoot = ".\nmuidi-test"
$targetDir = "$testRoot\target"
$reparseTarget = "$testRoot\external"

# Clean up from previous runs
Remove-Item -Path $testRoot -Recurse -Force -ErrorAction SilentlyContinue
New-Item -Path $testRoot -ItemType Directory | Out-Null
New-Item -Path $targetDir -ItemType Directory | Out-Null
New-Item -Path $reparseTarget -ItemType Directory | Out-Null

# Add files and subdirs to target
New-Item -Path "$targetDir\file1.txt" -ItemType File | Out-Null
New-Item -Path "$targetDir\subdir" -ItemType Directory | Out-Null
New-Item -Path "$targetDir\subdir\file2.txt" -ItemType File | Out-Null

# Create a junction (reparse point) to the external directory
cmd /c mklink /J "$targetDir\junction" "$reparseTarget" | Out-Null

# --- Additional test cases ---

# 1. Symlink to file
New-Item -Path "$targetDir\original.txt" -ItemType File -Value "Hello" | Out-Null
New-Item -Path "$targetDir\link-to-file.txt" -ItemType SymbolicLink -Target "$targetDir\original.txt" | Out-Null

# 2. Symlink to directory
New-Item -Path "$targetDir\original-dir" -ItemType Directory | Out-Null
New-Item -Path "$targetDir\link-to-dir" -ItemType SymbolicLink -Target "$targetDir\original-dir" | Out-Null

# 3. Readonly file
New-Item -Path "$targetDir\readonly.txt" -ItemType File -Value "readonly" | Out-Null
attrib +r "$targetDir\readonly.txt"

# 4. Nested directories with file
New-Item -Path "$targetDir\nested\deep" -ItemType Directory -Force | Out-Null
New-Item -Path "$targetDir\nested\deep\file.txt" -ItemType File -Value "nested file" | Out-Null

# Sanity check before deletion
Write-Host "Before deletion:"
Get-ChildItem -Recurse -Force -Path $testRoot

# Run nmuidi
Write-Host "`nRunning nmuidi on $targetDir..."
# nmuidi.exe "$targetDir"
..\target\debug\nmuidi.exe "$targetDir"

Write-Host "`nAfter deletion:"
Get-ChildItem -Recurse -Force -Path $testRoot

if (Test-Path $targetDir) {
    Write-Host "`nTarget directory was NOT deleted."
}

if (-Not (Test-Path $reparseTarget)) {
    Write-Host "Reparse target directory was incorrectly deleted."
}

if (Test-Path "$targetDir\link-to-file.txt") {
    Write-Host "Symlink to file was NOT deleted."
}

if (Test-Path "$targetDir\link-to-dir") {
    Write-Host "Symlink to directory was NOT deleted."
}

if (Test-Path "$targetDir\readonly.txt") {
    Write-Host "Readonly file was NOT deleted."
}

if (Test-Path "$targetDir\nested") {
    Write-Host "Nested directories were NOT deleted."
}