fix: resolve GitHub Actions workflow failures

## Fixed dependency updater workflow
- Added explicit workspace directory handling
- Improved error handling with clear error messages
- Fixed update summary file reading with error suppression
- Added error output for debugging failures

## Fixed Docker build workflow
- Added memory constraints (8GB/16GB swap) to prevent OOM
- Fixed Dockerfile to use npm scripts instead of direct node execution
- Added fallback mechanism: optimized rebuild → regular rebuild → error
- Added buildx ID reference and no-cache filter for db-builder stage

These changes should resolve both workflow failures and make the CI/CD pipeline more robust.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Dockerfile

@@ -34,7 +34,10 @@ RUN apk add --no-cache git ca-certificates && \
 ENV N8N_DOCS_PATH=/tmp/n8n-docs
 # Build the complete database with source code
 RUN mkdir -p data && \
-    node dist/scripts/rebuild-optimized.js
+    npm run rebuild:optimized || \
+    (echo "Warning: Optimized rebuild failed, trying regular rebuild" && \
+     npm run rebuild) || \
+    (echo "Error: Database build failed" && exit 1)
 
 # Stage 4: Minimal Runtime (no n8n packages)
 FROM node:20-alpine AS runtime