fix: use setup-dotnet built-in NuGet cache (#313)

* fix: use setup-dotnet built-in NuGet cache instead of actions/cache

The manual actions/cache step used ~/.nuget/packages which doesn't
resolve correctly on Windows runners. setup-dotnet's built-in cache
handles the platform-specific path automatically.

* perf: speed up CI by caching IntelliJ Platform and avoiding double build

- Cache ~/.intellijPlatform so the Rider SDK (~1GB) isn't re-downloaded
  on every run
- On master, run only publishPlugin (which already depends on
  buildPlugin) instead of running buildPlugin then publishPlugin
  separately, avoiding a full double .NET compile
- Add --parallel flag to Gradle for concurrent subproject execution

Author: MO2k4

.github/workflows/main.yml

@@ -24,30 +24,31 @@ jobs:
         uses: actions/setup-dotnet@v4
         with:
           dotnet-version: '8.x'
+          cache: true
+          cache-dependency-path: src/dotnet/*/*.csproj
 
       - name: Setup Gradle
         uses: gradle/actions/setup-gradle@0b6dd653ba04f4f93bf581ec31e66cbd7dcb644d # v4
 
-      - name: Cache NuGet packages
+      - name: Cache IntelliJ Platform
         uses: actions/cache@v4
         with:
-          path: ~/.nuget/packages
-          key: ${{ runner.os }}-nuget-${{ hashFiles('src/dotnet/*/*.csproj', 'src/dotnet/*.props') }}
-          restore-keys: |
-            ${{ runner.os }}-nuget-
+          path: ~/.intellijPlatform
+          key: intellij-${{ hashFiles('gradle.properties') }}
 
       - name: Build Plugin
-        run: ./gradlew buildPlugin --build-cache
+        if: github.ref != 'refs/heads/master'
+        run: ./gradlew buildPlugin --parallel --build-cache
+
+      - name: Build & Publish Plugin
+        if: github.ref == 'refs/heads/master'
+        run: ./gradlew publishPlugin -PBuildConfiguration="Release" -PPublishToken="$PUBLISH_KEY" --parallel --build-cache
+        env:
+          PUBLISH_KEY: ${{ secrets.PublishKey }}
 
       - name: Publish Artifact
         uses: actions/upload-artifact@v4
         with:
           name: Artifacts
           path: output
           retention-days: 7
-
-      - name: Publish plugins to jetbrains
-        run: ./gradlew publishPlugin -PBuildConfiguration="Release" -PPublishToken="$PUBLISH_KEY" --build-cache
-        env:
-          PUBLISH_KEY: ${{ secrets.PublishKey }}
-        if: github.event_name != 'pull_request' && github.ref == 'refs/heads/master'