Add prebuild directory and update git dot files

scripts/bootstrap_sdl_windows.ps1

@@ -1,11 +1,26 @@
+# One-time bootstrap: builds SDL3 from source and installs it into prebuilt/windows/.
+# Run this once after cloning. Re-run only when upgrading SDL.
 param(
-    [string]$BuildType = "Release"
+    [string]$SdlVersion = "3.2.10",
+    [string]$BuildType  = "Release"
 )
 
 $ProjectRoot = Resolve-Path "$PSScriptRoot\.."
-$SdlSource   = "$ProjectRoot\external\SDL"
-$BuildDir    = "$ProjectRoot\out\build\_sdl_build\windows"
+$BuildDir    = "$ProjectRoot\out\build\_sdl_bootstrap\windows"
 $PrebuiltDir = "$ProjectRoot\prebuilt\windows"
+$SdlSource   = "$BuildDir\SDL-src"
+
+# Download SDL source if not already present
+if (-not (Test-Path $SdlSource)) {
+    Write-Host "`n=== Downloading SDL3 $SdlVersion ===" -ForegroundColor Cyan
+    New-Item -ItemType Directory -Force -Path $BuildDir | Out-Null
+    $Archive = "$BuildDir\SDL-$SdlVersion.tar.gz"
+    Invoke-WebRequest -Uri "https://github.com/libsdl-org/SDL/archive/refs/tags/release-$SdlVersion.tar.gz" `
+        -OutFile $Archive
+    tar -xf $Archive -C $BuildDir
+    Rename-Item "$BuildDir\SDL-release-$SdlVersion" "SDL-src"
+    Remove-Item $Archive
+}
 
 function Build-SDL {
     param([string]$LinkType)
@@ -17,7 +32,6 @@ function Build-SDL {
 
     Write-Host "`n=== Building SDL3 ($LinkType) for Windows ===" -ForegroundColor Cyan
 
-    # Wipe any stale build directory to avoid corrupted cache issues
     if (Test-Path $BuildOut) {
         Write-Host "Removing stale build directory: $BuildOut" -ForegroundColor Yellow
         Remove-Item -Recurse -Force $BuildOut