ci: switch to windows powershell to fix runner account path issues

.gitea/workflows/build.yaml

@@ -8,13 +8,15 @@ on:
 jobs:
   build:
     runs-on: windows-latest
+    defaults:
+      run:
+        shell: powershell
 
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
 
       - name: Install Rust
-        shell: pwsh
         run: |
           $installDir = "$env:USERPROFILE\.cargo\bin"
           if (-not (Test-Path $installDir)) {
@@ -28,15 +30,13 @@ jobs:
         run: choco install llvm --no-progress
 
       - name: Build Client
-        shell: pwsh
         run: |
-          # Manually ensure cargo is in path for this specific shell session
+          # Ensure cargo is in path for this specific shell session
           $env:Path = "$env:USERPROFILE\.cargo\bin;" + $env:Path
           cd client
           cargo build --release
 
       - name: Prepare Binaries for Installer
-        shell: pwsh
         run: |
           New-Item -ItemType Directory -Force -Path bin
           Copy-Item "client\target\release\meshvpn-client.exe" "bin\client.exe"
@@ -46,7 +46,6 @@ jobs:
         run: choco install wixtoolset --no-progress
 
       - name: Build MSI Installer
-        shell: pwsh
         run: |
           # Add WiX bin to path (common choco install path)
           $env:Path += ";C:\Program Files (x86)\WiX Toolset v3\bin"