ci: add platform triage workflow for issue auto-assign

When a new issue selects macOS as platform, automatically labels it
platform:macos and assigns afonsojramos. Linux issues get labeled
platform:linux.

cc

.github/workflows/issue-platform-triage.yml

@@ -0,0 +1,54 @@
+name: Platform triage
+
+on:
+  issues:
+    types: [opened]
+
+permissions:
+  issues: write
+
+jobs:
+  triage:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Parse platform from issue body
+        id: platform
+        uses: actions/github-script@v7
+        with:
+          script: |
+            const body = context.payload.issue.body || '';
+            // GitHub issue forms render dropdowns as "### Label\n\nValue"
+            const platformMatch = body.match(/### Platform\s*\n\n(.+)/);
+            const platform = platformMatch ? platformMatch[1].trim() : '';
+            core.setOutput('value', platform);
+
+      - name: Label and assign macOS issues
+        if: steps.platform.outputs.value == 'macOS'
+        uses: actions/github-script@v7
+        with:
+          script: |
+            const issue = context.payload.issue.number;
+            await github.rest.issues.addLabels({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: issue,
+              labels: ['platform:macos']
+            });
+            await github.rest.issues.addAssignees({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: issue,
+              assignees: ['afonsojramos']
+            });
+
+      - name: Label Linux issues
+        if: steps.platform.outputs.value == 'Linux'
+        uses: actions/github-script@v7
+        with:
+          script: |
+            await github.rest.issues.addLabels({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: context.payload.issue.number,
+              labels: ['platform:linux']
+            });