feat: add GitHub Actions CI/CD workflows and local test runner

.github/workflows/ci.yml

@@ -0,0 +1,73 @@
+name: CI
+
+"on":
+    push:
+        branches:
+            - develop
+            - "feature/**"
+            - "fix/**"
+            - "hotfix/**"
+    pull_request:
+        branches:
+            - develop
+            - master
+
+# RUNNING_LOCALLY is set to 'true' by ci-cd-test-run.ps1 via act's --env flag.
+# On real GitHub Actions the variable is empty, so steps gated on it run normally.
+env:
+    RUNNING_LOCALLY: ""
+
+jobs:
+    validate-branch:
+        name: Validate Branch Name
+        runs-on: ubuntu-latest
+        if: github.event_name == 'pull_request'
+        steps:
+            - name: Check branch naming convention
+              env:
+                  BRANCH: ${{ github.head_ref }}
+              run: |
+                  if [[ ! "$BRANCH" =~ ^(feature|fix|hotfix)/.+ ]] && [[ "$BRANCH" != "develop" ]]; then
+                    echo "::error::Branch '$BRANCH' does not follow naming conventions."
+                    echo "::error::PR source branches must be 'develop' or prefixed with 'feature/', 'fix/', or 'hotfix/'."
+                    exit 1
+                  fi
+                  echo "Branch '$BRANCH' follows naming conventions."
+
+    build-and-test:
+        name: Build & Test (${{ matrix.framework }})
+        needs: validate-branch
+        # Run on push events (validate-branch skipped) OR on valid PRs (validate-branch succeeded)
+        if: always() && (needs.validate-branch.result == 'success' || needs.validate-branch.result == 'skipped')
+        runs-on: ubuntu-latest
+        strategy:
+            fail-fast: false
+            matrix:
+                framework: ["net8.0", "net9.0", "net10.0"]
+        steps:
+            - uses: actions/checkout@v5
+            - name: Setup .NET
+              uses: actions/setup-dotnet@v5
+              with:
+                  dotnet-version: |
+                      8.0.x
+                      9.0.x
+                      10.0.x
+            - name: Restore
+              run: dotnet restore src/System.Text.Json.Stream.CI.slnf
+            - name: Build
+              run: dotnet build src/System.Text.Json.Stream.CI.slnf --no-restore --configuration Release -p:GeneratePackageOnBuild=false
+            - name: Test (${{ matrix.framework }})
+              run: |
+                  dotnet test src/System.Text.Json.Stream.Tests/System.Text.Json.Stream.Tests.csproj \
+                    --no-build --no-restore \
+                    --configuration Release --framework ${{ matrix.framework }} \
+                    --logger "trx;LogFileName=test-results-${{ matrix.framework }}.trx"
+            - name: Upload test results
+              uses: actions/upload-artifact@v7
+              # Skipped when running locally via act (RUNNING_LOCALLY=true passed by ci-cd-test-run.ps1).
+              # On real GitHub Actions RUNNING_LOCALLY is empty, so the step runs and failures are fatal.
+              if: always() && env.RUNNING_LOCALLY == ''
+              with:
+                  name: test-results-${{ matrix.framework }}
+                  path: "**/*.trx"

.github/workflows/release.yml

@@ -0,0 +1,88 @@
+name: Release
+
+"on":
+    push:
+        branches:
+            - master
+
+jobs:
+    release:
+        name: Build, Test & Publish to NuGet
+        runs-on: ubuntu-latest
+        permissions:
+            contents: write
+        steps:
+            - uses: actions/checkout@v5
+              with:
+                  fetch-depth: 0
+            - name: Setup .NET
+              uses: actions/setup-dotnet@v5
+              with:
+                  dotnet-version: |
+                      8.0.x
+                      9.0.x
+                      10.0.x
+            - name: Restore
+              run: dotnet restore src/System.Text.Json.Stream.CI.slnf
+            - name: Build
+              run: dotnet build src/System.Text.Json.Stream.CI.slnf --no-restore --configuration Release -p:GeneratePackageOnBuild=false
+            - name: Test (net8.0)
+              run: |
+                  dotnet test src/System.Text.Json.Stream.Tests/System.Text.Json.Stream.Tests.csproj \
+                    --no-build --no-restore --configuration Release --framework net8.0
+            - name: Test (net9.0)
+              run: |
+                  dotnet test src/System.Text.Json.Stream.Tests/System.Text.Json.Stream.Tests.csproj \
+                    --no-build --no-restore --configuration Release --framework net9.0
+            - name: Test (net10.0)
+              run: |
+                  dotnet test src/System.Text.Json.Stream.Tests/System.Text.Json.Stream.Tests.csproj \
+                    --no-build --no-restore --configuration Release --framework net10.0
+            - name: Extract version from csproj
+              id: version
+              run: |
+                  VERSION=$(grep -m1 '<Version>' src/System.Text.Json.Stream/System.Text.Json.Stream.csproj \
+                    | sed 's/.*<Version>//;s/<\/Version>.*//' \
+                    | tr -d '[:space:]')
+                  echo "version=$VERSION" >> $GITHUB_OUTPUT
+                  echo "tag=v$VERSION" >> $GITHUB_OUTPUT
+                  echo "Resolved version: $VERSION"
+            - name: Check if this version was already released
+              id: tag_check
+              run: |
+                  if git ls-remote --tags origin "refs/tags/v${{ steps.version.outputs.version }}" | grep -q .; then
+                    echo "exists=true" >> $GITHUB_OUTPUT
+                  else
+                    echo "exists=false" >> $GITHUB_OUTPUT
+                  fi
+            - name: Pack NuGet package
+              if: steps.tag_check.outputs.exists == 'false'
+              run: |
+                  dotnet pack src/System.Text.Json.Stream/System.Text.Json.Stream.csproj \
+                    --no-build --configuration Release --output ./artifacts
+            - name: Create GitHub Release
+              if: steps.tag_check.outputs.exists == 'false'
+              env:
+                  GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+              run: |
+                  gh release create "${{ steps.version.outputs.tag }}" \
+                    --title "Release ${{ steps.version.outputs.tag }}" \
+                    --generate-notes \
+                    ./artifacts/Utf8JsonAsyncStreamReader.${{ steps.version.outputs.version }}.nupkg \
+                    ./artifacts/Utf8JsonAsyncStreamReader.${{ steps.version.outputs.version }}.snupkg
+            - name: Push Utf8JsonAsyncStreamReader to NuGet.org
+              if: steps.tag_check.outputs.exists == 'false'
+              run: |
+                  dotnet nuget push \
+                    "./artifacts/Utf8JsonAsyncStreamReader.${{ steps.version.outputs.version }}.nupkg" \
+                    --api-key ${{ secrets.NUGET_API_KEY }} \
+                    --source https://api.nuget.org/v3/index.json \
+                    --skip-duplicate
+            - name: Push Utf8JsonAsyncStreamReader symbols to NuGet.org
+              if: steps.tag_check.outputs.exists == 'false'
+              run: |
+                  dotnet nuget push \
+                    "./artifacts/Utf8JsonAsyncStreamReader.${{ steps.version.outputs.version }}.snupkg" \
+                    --api-key ${{ secrets.NUGET_API_KEY }} \
+                    --source https://api.nuget.org/v3/index.json \
+                    --skip-duplicate