Add F4SE plugin template

Create a minimal Fallout 4 F4SE/CommonLibF4 starter repo with build, packaging, install, and rename scripts, plus initial plugin source, headers, and xmake configuration.

scripts/rename-template.ps1

@@ -0,0 +1,23 @@
+param(
+    [Parameter(Mandatory=$true)]
+    [string]$NewName,
+
+    [string]$Author = "YourName"
+)
+
+$ErrorActionPreference = "Stop"
+
+$root = Split-Path -Parent $PSScriptRoot
+$files = Get-ChildItem -Path $root -Recurse -File | Where-Object {
+    $_.FullName -notmatch "\\\.git\\" -and
+    $_.FullName -notmatch "\\lib\\commonlibf4\\"
+}
+
+foreach ($file in $files) {
+    $content = Get-Content $file.FullName -Raw
+    $content = $content.Replace("F4SEPluginTemplate", $NewName)
+    $content = $content.Replace("YourName", $Author)
+    Set-Content -Path $file.FullName -Value $content -NoNewline
+}
+
+Write-Host "Renamed template references to $NewName"