fix: pin pnpm version in dockerfile to prevent corepack fetching latest

apps/web/Dockerfile

@@ -11,6 +11,7 @@ RUN apk update && \
     apk add --no-cache libc6-compat && \
     rm -rf /var/cache/apk/* /tmp/* || true && \
     corepack enable && \
+    corepack prepare pnpm@9.14.2 --activate && \
     npm install turbo@2.3.1 --global && \
     pnpm config set store-dir ~/.pnpm-store