fix(ci): copy .npmrc before pnpm install in all Dockerfiles

The .npmrc file contains supportedArchitectures settings to force pnpm
to install glibc x64 binaries for native modules like matrix-sdk-crypto-nodejs.

Without copying this file into the Docker image, pnpm defaults to the
platform's native behavior which may skip or install incorrect binaries.

.woodpecker/ci.yml

@@ -29,10 +29,9 @@ when:
         - ".trivyignore"
 
 variables:
-  - &node_image "node:24-slim"
+  - &node_image "node:24-alpine"
   - &install_deps |
     corepack enable
-    apt-get update && apt-get install -y --no-install-recommends python3 make g++
     pnpm config set store-dir /root/.local/share/pnpm/store
     pnpm install --frozen-lockfile
   - &use_deps |