Add deployment support for Node.js, Docker, and additional serverless runtimes

## Summary

Codra currently runs exclusively on Cloudflare Workers. This issue tracks adding deployment support for Node.js, Docker, and other serverless runtimes so developers can run Codra on infrastructure they already control.

The goal is one codebase, multiple deployment targets, not separate branches or parallel implementations.

## Scope

### Node.js Server Deployment

A conventional always-on server path using Node.js and PM2 for EC2, Hetzner, DigitalOcean Droplets, or any VM.

- Replace Cloudflare Queues with BullMQ on Redis or a Postgres-backed job table
- Replace KV bindings with Redis for session storage and config caching
- Split the single Workers entry point into separate HTTP server and queue worker processes
- Support environment-variable-based configuration with no Wrangler dependency

### Docker-First Deployment

A `docker-compose.yml` that bundles the app, worker process, and a Postgres instance so the full stack can be brought up with a single command.

- Targets platforms like Coolify, Railway, Render, and Fly.io
- Should work on any machine with Docker installed with no extra tooling required

### Serverless Runtime Adapters

Adapter support for serverless runtimes outside Cloudflare Workers.

- Vercel Functions
- Other Node.js-compatible serverless runtimes

## Out of Scope

- Kubernetes or Helm chart deployment (can be a follow-up)
- Support for non-GitHub VCS providers (separate issue)

## Related

- Blog post: [https://devarshi.dev/blog/codra-self-hosted-ai-code-review](https://devarshi.dev/blog/codra-self-hosted-ai-code-review)
- Discord discussion: [https://discord.com/channels/595317990191398933/1516486329570169062](https://discord.com/channels/595317990191398933/1516486329570169062)