Fix SSH tunnel Docker build for Dokploy deployment

Changes:
- Fix Dockerfile COPY path from ../secrets to secrets/ (Docker doesn't allow parent directory access)
- Create ssh-tunnel/secrets/ directory structure with comprehensive README
- Add .dockerignore for ssh-tunnel to optimize build context
- Add DOKPLOY_DEPLOYMENT.md with complete deployment guide including:
  * SSH key configuration options (repository, secrets manager, BuildKit)
  * Environment variables setup
  * Step-by-step deployment instructions
  * Troubleshooting section
  * Security best practices
- Update .gitignore to allow secrets/README.md files for documentation

This resolves the Dokploy build failure: "failed to calculate checksum of ref... /secrets/roa_oracle_server: not found"

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

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

.gitignore

@@ -407,6 +407,8 @@ scan_*.json
 sdist/
 sdist/
 secrets/
+# Allow documentation in secrets directories
+!**/secrets/README.md
 security_*.json
 share/python-wheels/
 sqlnet.ora