Make dependency installation architecture-aware

Detect processor architecture and install appropriate versions:
- ARM64: Manual LLVM/Ruby installation (Scoop has x64-only versions)
- x64: Use Scoop for all dependencies

This allows the same workflow to work on both x64 and ARM64 runners.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: WebKit ARM64 Builder

.github/workflows/build.yml

@@ -254,8 +254,11 @@ jobs:
     runs-on: ${{ matrix.runner }}
     timeout-minutes: 90
     steps:
-      - name: Install dependencies for ARM64 Windows
+      - name: Install dependencies for Windows
         run: |
+          # Detect architecture
+          $isARM64 = $env:PROCESSOR_ARCHITECTURE -eq "ARM64"
+          
           # Install Scoop if not available
           if (!(Get-Command scoop -ErrorAction SilentlyContinue)) {
             Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope CurrentUser -Force
@@ -264,22 +267,33 @@ jobs:
             echo "$env:USERPROFILE\scoop\shims" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
           }
           
-          # Install tools via Scoop (except Ruby and LLVM which need ARM64 versions)
+          # Install tools via Scoop
           scoop install cmake ninja python perl
           
-          # Install LLVM ARM64 manually (Scoop downloads x64 on ARM64)
-          $llvmUrl = "https://github.com/llvm/llvm-project/releases/download/llvmorg-19.1.4/LLVM-19.1.4-woa64.exe"
-          $llvmExe = "$env:TEMP\llvm.exe"
-          Invoke-WebRequest -Uri $llvmUrl -OutFile $llvmExe
-          Start-Process -FilePath $llvmExe -ArgumentList "/S", "/D=C:\LLVM" -Wait
-          echo "C:\LLVM\bin" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
+          # Install LLVM - use correct architecture version
+          if ($isARM64) {
+            # Scoop installs x64 LLVM on ARM64, need to manually install ARM64 version
+            $llvmUrl = "https://github.com/llvm/llvm-project/releases/download/llvmorg-19.1.4/LLVM-19.1.4-woa64.exe"
+            $llvmExe = "$env:TEMP\llvm.exe"
+            Invoke-WebRequest -Uri $llvmUrl -OutFile $llvmExe
+            Start-Process -FilePath $llvmExe -ArgumentList "/S", "/D=C:\LLVM" -Wait
+            echo "C:\LLVM\bin" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
+          } else {
+            # x64 can use Scoop's LLVM
+            scoop install llvm
+          }
           
-          # Install Ruby manually since Scoop's Ruby fails on ARM64
-          $rubyUrl = "https://github.com/oneclick/rubyinstaller2/releases/download/RubyInstaller-3.3.6-1/rubyinstaller-devkit-3.3.6-1-x64.exe"
-          $rubyExe = "$env:TEMP\ruby.exe"
-          Invoke-WebRequest -Uri $rubyUrl -OutFile $rubyExe
-          Start-Process -FilePath $rubyExe -ArgumentList "/VERYSILENT", "/NORESTART", "/DIR=C:\Ruby33-x64" -Wait
-          echo "C:\Ruby33-x64\bin" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
+          # Install Ruby manually on ARM64 (Scoop's Ruby fails on ARM64)
+          if ($isARM64) {
+            $rubyUrl = "https://github.com/oneclick/rubyinstaller2/releases/download/RubyInstaller-3.3.6-1/rubyinstaller-devkit-3.3.6-1-x64.exe"
+            $rubyExe = "$env:TEMP\ruby.exe"
+            Invoke-WebRequest -Uri $rubyUrl -OutFile $rubyExe
+            Start-Process -FilePath $rubyExe -ArgumentList "/VERYSILENT", "/NORESTART", "/DIR=C:\Ruby33-x64" -Wait
+            echo "C:\Ruby33-x64\bin" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
+          } else {
+            # x64 can use Scoop's Ruby
+            scoop install ruby
+          }
           
           # Install vcpkg
           git clone https://github.com/Microsoft/vcpkg.git C:\vcpkg