fix: intercept stdout writes to prevent JSON-RPC corruption in stdio mode (#673)

* fix: intercept process.stdout.write to prevent JSON-RPC corruption in stdio mode (#628, #627, #567)

Console method suppression alone was insufficient — native modules, n8n packages,
and third-party code can call process.stdout.write() directly, leaking debug output
(refCount, dbPath, clientVersion, protocolVersion, etc.) into the MCP JSON-RPC stream.

Added stdout write interceptor that only allows JSON-RPC messages through (objects
containing "jsonrpc" field). All other writes are redirected to stderr. This fixes
the flood of "Unexpected token is not valid JSON" warnings on every new Claude
Desktop chat.

Conceived by Romuald Członkowski - https://www.aiadvisors.pl/en

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

* ci: add Docker Hub login to fix buildx bootstrap rate limiting

GitHub-hosted runners hit Docker Hub anonymous pull limits when
setup-buildx-action pulls moby/buildkit. Add docker/login-action
for Docker Hub before setup-buildx-action in all 4 workflows:
docker-build.yml, docker-build-fast.yml, docker-build-n8n.yml, release.yml.

Uses DOCKERHUB_USERNAME and DOCKERHUB_TOKEN repository secrets.

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

---------

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

.github/workflows/docker-build.yml

@@ -71,13 +71,19 @@ jobs:
           "
           echo "✅ Synced package.runtime.json to version $VERSION"
 
+      - name: Log in to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
       - name: Set up QEMU
         uses: docker/setup-qemu-action@v3
-        
+
       - name: Set up Docker Buildx
         id: buildx
         uses: docker/setup-buildx-action@v3
-        
+
       - name: Log in to GitHub Container Registry
         if: github.event_name != 'pull_request'
         uses: docker/login-action@v3
@@ -85,7 +91,7 @@ jobs:
           registry: ${{ env.REGISTRY }}
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
-          
+
       - name: Extract metadata
         id: meta
         uses: docker/metadata-action@v5
@@ -173,13 +179,19 @@ jobs:
           "
           echo "✅ Synced package.runtime.json to version $VERSION"
 
+      - name: Log in to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
       - name: Set up QEMU
         uses: docker/setup-qemu-action@v3
-        
+
       - name: Set up Docker Buildx
         id: buildx
         uses: docker/setup-buildx-action@v3
-        
+
       - name: Log in to GitHub Container Registry
         if: github.event_name != 'pull_request'
         uses: docker/login-action@v3