feat: add semantic PR validation workflow

- Validates PR titles against conventional commit standards
- Adds helpful comments when titles don't follow format
- Auto-deletes comments when titles are fixed
- Uses standard GITHUB_TOKEN (no special app setup needed)
- Enforces consistency with semantic-release workflow

.github/workflows/semantic-pr.yml

@@ -0,0 +1,47 @@
+---
+name: Semantic PR
+
+on:
+  pull_request:
+    types: [opened, edited, synchronize]
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+  pull-requests: write
+
+jobs:
+  semantic-pr:
+    name: Validate PR
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    steps:
+      - name: Check PR Title
+        id: lint-pr-title
+        uses: amannn/action-semantic-pull-request@0723387faaf9b38adef4775cd42cfd5155ed6017 # v5.5.3
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Add PR error comment
+        uses: marocchino/sticky-pull-request-comment@d2ad0de260ae8b0235ce059e63f2949ba9e05943 # v2.9.3
+        if: always() && (steps.lint-pr-title.outputs.error_message != null)
+        with:
+          header: pr-title-lint-error
+          message: |
+            We require pull request titles to follow the [Conventional Commits specification](https://www.conventionalcommits.org/en/v1.0.0/) and it looks like your proposed title needs to be adjusted.
+
+            Details:
+
+            ```
+            ${{ steps.lint-pr-title.outputs.error_message }}
+            ```
+
+      - name: Delete PR error comment
+        uses: marocchino/sticky-pull-request-comment@d2ad0de260ae8b0235ce059e63f2949ba9e05943 # v2.9.3
+        if: ${{ steps.lint-pr-title.outputs.error_message == null }}
+        with:
+          header: pr-title-lint-error
+          delete: true