ci: Add validate-paths step to generate workflow

Runs the SUMMARY.md path validator after codegen, before link
validation. Ensures file paths stay in sync with their section headings.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: louis-pre

.github/workflows/generate.yml

@@ -66,6 +66,20 @@ jobs:
           commit_user_name: ${{ secrets.GIT_USER_NAME }}
           commit_user_email: ${{ secrets.GIT_USER_EMAIL }}
           commit_author: ${{ secrets.GIT_USER_NAME }} <${{ secrets.GIT_USER_EMAIL }}>
+  validate-paths:
+    name: Validate paths
+    needs: commit
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ github.head_ref }}
+      - name: Setup
+        uses: ./.github/actions/setup
+      - name: Validate SUMMARY.md paths
+        run: npm run validate-paths
   validate-links:
     name: Validate links
     needs: commit