Add PR artifact uploads and comments (#1401)

* Add PR artifact uploads and comments

Update the build workflow to handle pull request runs: make the main artifact upload conditional (skip for pull_request), add a separate upload step for PR artifacts with longer retention, and post a sticky PR comment containing a download link. Also adjust workflow permissions to allow pull-request write access and include updated artifact paths.

* Update build workflow: PR comments and artifacts

Add PR-facing comments and artifact wiring to the CI workflow. Post a sticky comment after Gradle tests to indicate artifacts availability, add an upload-artifact step with an id, and update the sticky-comment step to use the artifact output URL (steps.upload-artifact.outputs.artifact-url) and a consistent header. These changes make build artifacts discoverable on pull requests.

* Switch to a table

* update messaging

* Use `processing-bot`

.github/workflows/build.yml

@@ -24,10 +24,26 @@ jobs:
 
       - name: Build with Gradle
         run: ./gradlew test
+
+      - name: Add comment with binaries
+        if: ${{ github.event_name == 'pull_request' }}
+        uses: marocchino/sticky-pull-request-comment@v2
+        with:
+          header: artifacts
+          GITHUB_TOKEN: ${{ secrets.PR_PAT }}
+          message: |
+            Tests completed successfully. Build artifacts for this pull request will appear below once ready.
+            
+            ### Build Artifacts
+            | Platform | Link |
+            |:--|------------------------|
+
   build:
     name: (${{ matrix.os_prefix }}/${{ matrix.arch }}) Create Processing Build
     runs-on: ${{ matrix.os }}
     needs: test
+    permissions:
+      pull-requests: write
     strategy:
       fail-fast: false
       matrix:
@@ -64,7 +80,28 @@ jobs:
 
       - name: Add artifact
         uses: actions/upload-artifact@v4
+        if: ${{ github.event_name != 'pull_request' }}
         with:
           name: processing-${{ matrix.os_prefix }}-${{ matrix.arch }}-br_${{ github.ref_name }}
           retention-days: 1
-          path: app/build/compose/binaries/main/${{ matrix.binary }}
+          path: app/build/compose/binaries/main/${{ matrix.binary }}
+
+      - name: Add artifact for PR
+        if: ${{ github.event_name == 'pull_request' }}
+        id: upload-artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: processing-${{ matrix.os_prefix }}-${{ matrix.arch }}-pr_${{ github.event.pull_request.number }}
+          retention-days: 5
+          path: app/build/compose/binaries/main/${{ matrix.binary }}
+
+      - name: Add comment with binaries
+        if: ${{ github.event_name == 'pull_request' }}
+        uses: marocchino/sticky-pull-request-comment@v2
+        with:
+          append: true
+          header: artifacts
+          GITHUB_TOKEN: ${{ secrets.PR_PAT }}
+          message: |
+            |(${{ matrix.os_prefix }}/${{ matrix.arch }})|[Download processing-${{ matrix.os_prefix }}-${{ matrix.arch }}-pr_${{ github.event.pull_request.number }}](${{ steps.upload-artifact.outputs.artifact-url }})|
+