ci: pin pnpm to v10 in documents workflow

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.github/workflows/documents.yml

@@ -47,7 +47,7 @@ jobs:
       - name: Install dependencies
         run: |
           corepack enable
-          corepack prepare pnpm@latest --activate
+          corepack prepare pnpm@10 --activate
           pnpm install
         working-directory: docs