Initial import: KiCad zone resistance plugin

DC/AC resistance, power dissipation, and via/injection-area currents of
copper zone fills. KiCad 10 IPC-API plugin (kicad-python/kipy):
multi-layer via-coupled FDM solver, multi-part terminals via User.1/User.2
marker layers, pads as contacts, uniform-injection and equipotential
contact models, per-foil skin effect, optional solder/copper buildup on
mask openings. 54-case test suite incl. exact analytic references.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

deploy.ps1

@@ -0,0 +1,39 @@
+# Deploy the plugin into the KiCad user plugins directory.
+#   .\deploy.ps1                 -> NTFS junction (best for development)
+#   .\deploy.ps1 -Mode Copy      -> plain copy (no repo link)
+param(
+    [ValidateSet('Junction', 'Copy')]
+    [string]$Mode = 'Junction',
+    [string]$KiCadVersion = '10.0'
+)
+
+$src = $PSScriptRoot
+$pluginsDir = Join-Path ([Environment]::GetFolderPath('MyDocuments')) "KiCad\$KiCadVersion\plugins"
+$dst = Join-Path $pluginsDir 'fill-resistance'
+
+if (-not (Test-Path $pluginsDir)) {
+    Write-Error "KiCad plugins dir not found: $pluginsDir"
+    exit 1
+}
+
+if (Test-Path $dst) {
+    $item = Get-Item $dst -Force
+    if ($item.LinkType) {
+        # junction: rmdir removes the link only, never the target contents
+        cmd /c rmdir "$dst"
+    } else {
+        Remove-Item $dst -Recurse -Force
+    }
+}
+
+if ($Mode -eq 'Junction') {
+    New-Item -ItemType Junction -Path $dst -Target $src | Out-Null
+    Write-Host "junction created: $dst -> $src"
+} else {
+    $exclude = @('.venv', '.git', 'tests', 'smoke', '__pycache__', '.pytest_cache')
+    New-Item -ItemType Directory -Force $dst | Out-Null
+    Get-ChildItem $src -Force | Where-Object { $exclude -notcontains $_.Name } |
+        ForEach-Object { Copy-Item $_.FullName -Destination $dst -Recurse -Force }
+    Write-Host "copied plugin to: $dst"
+}
+Write-Host "Restart KiCad (or refresh plugins) and wait for the plugin venv build."