feat: implement data replication plugin for external database sync

[papica777-eng]

Summary

Implements a pull-based data replication plugin for StarbaseDB that enables syncing data from external data sources (PostgreSQL, MySQL, Turso, Cloudflare D1, StarbaseDB) into the internal Durable Object SQLite, turning the instance into a close-to-edge read replica.

Closes #72

Features

• Cursor-based incremental polling - efficiently fetches only new rows using a configurable cursor column
• • REST API for configuration, status monitoring, and manual sync triggers
• • Auto-creates target tables in internal SQLite from the source schema
• • Event callback system (onEvent) for downstream consumers
• • Multi-table support with per-table sync intervals
• • Admin-only access - all endpoints require admin authorization
• • Full test suite (9/9 passing)
    /claim Replicate data from external source to internal source with a Plugin #72

[papica777-eng]

Hi team! Just checking in on this PR. The implementation includes a full data replication plugin with cursor-based incremental polling, multi-table support, REST API configuration, and a complete test suite (9/9 passing). Let me know if there's anything you'd like me to adjust. Happy to iterate!