[Phase 1] Endpoint Model Restructure - Schema + Model + Repository

## Overview

Restructure endpoint model following K8s Service/ReplicaSet pattern. Create new deployment tables and migrate existing data while maintaining backward compatibility.

## Scope

- Create deployment_revisions, deployment_auto_scaling_policies, deployment_policies tables
- Update EndpointRow and RoutingRow with new columns
- Implement SQLAlchemy models and Repository CRUD methods
- Migrate existing endpoint data to new structure
- Ensure existing API compatibility

JIRA Issue: BA-3416