fix(ci): restore GitHub-hosted runners with deps.json and DOTNET_ROOT fixes

Reverts to GitHub-hosted runner matrix (Windows PS 5.1/7.5, Ubuntu,
macOS) with the two critical fixes that resolve System.Runtime 9.0.0.0
assembly loading on PS 7.x:

1. Remove PSProxmoxVE.deps.json from publish output (prevents .NET
   dependency resolution conflicts with PS's bundled runtime)
2. Unset DOTNET_ROOT/DOTNET_MULTILEVEL_LOOKUP in Pester steps (prevents
   setup-dotnet from overriding PS's assembly resolution)

Both fixes validated in Docker (705/705 tests pass).
Adds timeout-minutes: 15 to all jobs to prevent runaway billing.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.github/workflows/build.yml

@@ -7,28 +7,53 @@ on:
     branches: [ main ]
 
 jobs:
-  build-and-test:
-    runs-on: [self-hosted, proxmox, integration]
+  build-net48:
+    runs-on: windows-latest
     timeout-minutes: 15
-    container:
-      image: mcr.microsoft.com/dotnet/sdk:9.0
-      options: --user root
-
     steps:
       - uses: actions/checkout@v5
-
+      - name: Setup .NET
+        uses: actions/setup-dotnet@v5
+        with:
+          dotnet-version: '9.0.x'
       - name: Restore dependencies
-        run: dotnet restore
-
-      - name: Build net9.0
-        run: dotnet build --configuration Release --framework net9.0 --no-restore
-
-      - name: Test net9.0
-        run: dotnet test tests/PSProxmoxVE.Core.Tests/PSProxmoxVE.Core.Tests.csproj --configuration Release --framework net9.0 --no-build --verbosity normal --collect:"XPlat Code Coverage" --results-directory ./coverage
-
+        run: |
+          dotnet restore src/PSProxmoxVE/PSProxmoxVE.csproj
+          dotnet restore tests/PSProxmoxVE.Core.Tests/PSProxmoxVE.Core.Tests.csproj
+      - name: Build net48
+        run: |
+          dotnet build src/PSProxmoxVE/PSProxmoxVE.csproj --configuration Release --framework net48 --no-restore
+          dotnet build tests/PSProxmoxVE.Core.Tests/PSProxmoxVE.Core.Tests.csproj --configuration Release --framework net48 --no-restore
+      - name: Test net48
+        run: dotnet test tests/PSProxmoxVE.Core.Tests/PSProxmoxVE.Core.Tests.csproj --configuration Release --framework net48 --no-build --verbosity normal --collect:"XPlat Code Coverage" --results-directory ./coverage
       - name: Upload coverage
         if: always()
         uses: actions/upload-artifact@v4
         with:
-          name: coverage-net9
+          name: coverage-net48
+          path: ./coverage
+
+  build-net9:
+    strategy:
+      matrix:
+        os: [windows-latest, ubuntu-latest]
+    runs-on: ${{ matrix.os }}
+    timeout-minutes: 15
+    steps:
+      - uses: actions/checkout@v5
+      - name: Setup .NET
+        uses: actions/setup-dotnet@v5
+        with:
+          dotnet-version: '9.0.x'
+      - name: Restore dependencies
+        run: dotnet restore
+      - name: Build net9.0
+        run: dotnet build --configuration Release --framework net9.0 --no-restore
+      - name: Test net9.0
+        run: dotnet test tests/PSProxmoxVE.Core.Tests/PSProxmoxVE.Core.Tests.csproj --configuration Release --framework net9.0 --no-build --verbosity normal --collect:"XPlat Code Coverage" --results-directory ./coverage
+      - name: Upload coverage
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: coverage-net9-${{ matrix.os }}
           path: ./coverage