ci: add proto generation freshness check

.github/workflows/proto-check.yml

@@ -0,0 +1,42 @@
+name: Proto Generation Check
+
+on:
+  pull_request:
+    paths:
+      - 'proto/**'
+      - 'src/generated/**'
+      - 'docs/api/**'
+      - 'Makefile'
+
+jobs:
+  proto-freshness:
+    if: github.event.pull_request.head.repo.full_name == github.repository
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-go@v5
+        with:
+          go-version: '1.23'
+          cache: false
+
+      - name: Install buf and protoc plugins
+        run: make install-buf install-plugins
+        env:
+          GOPROXY: direct
+          GOPRIVATE: github.com/SebastienMelki
+
+      - name: Run proto generation
+        run: make generate
+
+      - name: Verify generated code is up to date
+        run: |
+          if ! git diff --exit-code src/generated/ docs/api/; then
+            echo ""
+            echo "============================================================"
+            echo "ERROR: Proto-generated code is out of date."
+            echo "Run 'make generate' locally and commit the updated files."
+            echo "============================================================"
+            exit 1
+          fi
+          echo "Proto-generated code is up to date."