feat: Phase LIVE integration - Production automation and deployment fixes

## Railway Deployment Fixes
- Fix railway.toml startCommand (remove incorrect 'cd backend')
- Enhance Dockerfile with security, health checks, and proper user permissions
- Add comprehensive deployment fix documentation (RAILWAY_DEPLOY_FIX.md)

## Phase Q/Q2 Integration
- Add GitHub webhooks router (/api/webhooks/github) for PR automation
- Integrate Prism Console at /prism endpoint
- Add GITHUB_TOKEN and GITHUB_WEBHOOK_SECRET to config
- Update .env.example with webhook secret

## Documentation
- Create comprehensive GitHub setup guide (GITHUB_SETUP_GUIDE.md)
- Document branch protection, merge queue, and webhook configuration
- Include troubleshooting and testing procedures

## Related
- Phase Q: Merge Queue & Automation (PR #78 - merged)
- Phase Q2: PR Action Intelligence (PR #85 - open)
- Phase 2.5: Infrastructure decisions (PR #63 - open)

This brings the automation stack online and stabilizes Railway deployments.

backend/app/config.py

@@ -56,6 +56,10 @@ class Settings(BaseSettings):
     BLOCKCHAIN_DIFFICULTY: int = 4
     MINING_REWARD: float = 50.0
 
+    # GitHub Automation (Phase Q)
+    GITHUB_TOKEN: str = ""
+    GITHUB_WEBHOOK_SECRET: str = ""
+
     class Config:
         env_file = ".env"
         case_sensitive = True