feat: Add Scaleway Serverless Container deployment

[kaaloo]

Overview

This PR adds Docker containerization and GitHub Actions workflow for deploying the DVF MCP app to Scaleway Serverless Containers.

Changes

• Dockerfile: Multi-stage build using Node.js 22 Alpine
  • Installs dependencies and builds frontend with Vite
  • Uses tsx for runtime execution
  • Exposes port 3001
• GitHub Actions Workflow (.github/workflows/deploy.yml):
  • Builds and pushes Docker image to Scaleway Container Registry
  • Deploys to Scaleway Serverless Container using Scaleway CLI
• .env.example: Template for required environment variables

Prerequisites

Before merging, the following must be configured in Scaleway Console:

1. Container Registry namespace
2. Serverless Container resource
3. GitHub Secrets (see .env.example for required values)

See planning documentation for detailed setup instructions.

Notes

• Workflow only triggers on push to main branch
• Domain name configuration is pending and can be added later
• Local Docker build verified successfully