Add PR writer workflow for labeling and commenting

This workflow automates PR labeling and commenting with firmware build stats and artifact links.

.github/workflows/pr-writer.yml

@@ -0,0 +1,157 @@
+name: PR writes (label + comment)
+
+on:
+  pull_request_target:
+    types: [opened, synchronize, reopened]
+
+permissions:
+  contents: read
+  pull-requests: write
+  issues: write
+
+jobs:
+  label:
+    runs-on: ubuntu-latest
+    steps:
+      # Safe: labeler reads files from the base repo by default in pull_request_target context.
+      # Do NOT checkout PR head.
+      - uses: actions/labeler@v5
+
+  comment_firmware:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Find the matching CI run for this PR SHA
+        id: find_run
+        uses: actions/github-script@v8
+        with:
+          script: |
+            const owner = context.repo.owner;
+            const repo = context.repo.repo;
+            const pr = context.payload.pull_request;
+            const headSha = pr.head.sha;
+
+            const { data } = await github.rest.actions.listWorkflowRunsForRepo({
+                owner,
+                repo,
+                event: "pull_request",
+                per_page: 50,
+            });
+
+            const run = data.workflow_runs.find(r => r.head_sha === headSha && r.name === "CI (build)");
+            if (!run) core.setFailed(`No matching CI (build) run found for head_sha=${headSha}.`);
+
+            core.setOutput("run_id", String(run.id));
+            core.setOutput("run_html_url", run.html_url);
+
+      - name: Locate artifact IDs in the CI run
+        id: artifacts
+        uses: actions/github-script@v8
+        with:
+          script: |
+            const owner = context.repo.owner;
+            const repo = context.repo.repo;
+            const runId = Number("${{ steps.find_run.outputs.run_id }}");
+
+            const { data } = await github.rest.actions.listWorkflowRunArtifacts({
+                owner,
+                repo,
+                run_id: runId,
+                per_page: 100,
+            });
+
+            const artifacts = data.artifacts || [];
+            const fw = artifacts.find(a => a.name === "firmware-bin");
+            const meta = artifacts.find(a => a.name === "build-meta");
+
+            if (!meta) core.setFailed("build-meta artifact not found in CI run artifacts.");
+            // firmware-bin is nice-to-have for linking; fail if you want.
+            core.setOutput("fw_id", fw ? String(fw.id) : "");
+            core.setOutput("meta_id", String(meta.id));
+
+      - name: Download build-meta artifact zip and extract pio.log
+        id: parse_log
+        shell: bash
+        env:
+          OWNER: ${{ github.repository_owner }}
+          REPO: ${{ github.event.repository.name }}
+          META_ID: ${{ steps.artifacts.outputs.meta_id }}
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          set -euo pipefail
+
+          # Download artifact zip via GitHub API (will redirect to blob storage; -L follows)
+          api="https://api.github.com/repos/${OWNER}/${REPO}/actions/artifacts/${META_ID}/zip"
+          curl -sSL \
+            -H "Authorization: Bearer ${GH_TOKEN}" \
+            -H "X-GitHub-Api-Version: 2022-11-28" \
+            -o build-meta.zip \
+            "${api}"
+
+          mkdir -p build-meta
+          unzip -q build-meta.zip -d build-meta
+
+          if [[ ! -f build-meta/pio.log ]]; then
+            echo "pio.log not found inside build-meta artifact"
+            echo "ram_line=" >> "$GITHUB_OUTPUT"
+            echo "flash_line=" >> "$GITHUB_OUTPUT"
+            exit 0
+          fi
+
+          ram_line="$(grep -E "RAM:\\s" -m1 build-meta/pio.log || true)"
+          flash_line="$(grep -E "Flash:\\s" -m1 build-meta/pio.log || true)"
+
+          echo "ram_line=${ram_line}" >> "$GITHUB_OUTPUT"
+          echo "flash_line=${flash_line}" >> "$GITHUB_OUTPUT"
+
+      - name: Post/update PR comment with RAM/Flash + artifact links
+        uses: actions/github-script@v8
+        with:
+          script: |
+            const owner = context.repo.owner;
+            const repo = context.repo.repo;
+            const prNumber = context.payload.pull_request.number;
+
+            const runId = Number("${{ steps.find_run.outputs.run_id }}");
+            const runUrl = "${{ steps.find_run.outputs.run_html_url }}";
+
+            const marker = '<!-- firmware-stats -->';
+            const ram = `${{ steps.parse_log.outputs.ram_line }}`.trim();
+            const flash = `${{ steps.parse_log.outputs.flash_line }}`.trim();
+
+            const fwId = `${{ steps.artifacts.outputs.fw_id }}`.trim();
+            const metaId = `${{ steps.artifacts.outputs.meta_id }}`.trim();
+
+            const fwUrl = fwId ? `https://github.com/${owner}/${repo}/actions/runs/${runId}/artifacts/${fwId}` : null;
+            const metaUrl = metaId ? `https://github.com/${owner}/${repo}/actions/runs/${runId}/artifacts/${metaId}` : null;
+
+            const body =
+              `${marker}\n**Firmware build stats**\n\n` +
+              `\`\`\`\n${ram || "RAM: not found"}\n${flash || "Flash: not found"}\n\`\`\`\n\n` +
+              `**Artifacts**\n` +
+              `- CI run: ${runUrl}\n` +
+              `- Firmware binary: ${fwUrl ? `[firmware-bin](${fwUrl})` : "artifact not found"}\n` +
+              `- Build logs: ${metaUrl ? `[build-meta](${metaUrl})` : "artifact not found"}`;
+
+            const { data: comments } = await github.rest.issues.listComments({
+              owner,
+              repo,
+              issue_number: prNumber,
+              per_page: 100,
+            });
+
+            const existing = comments.find(c => (c.body || "").includes(marker));
+            if (existing) {
+              await github.rest.issues.updateComment({
+                owner,
+                repo,
+                comment_id: existing.id,
+                body,
+              });
+            } else {
+              await github.rest.issues.createComment({
+                owner,
+                repo,
+                issue_number: prNumber,
+                body,
+              });
+            }