Add demo database dump for RefApp 3.6.0 / Core 2.8.4 (#110)

Generated from a fresh OpenMRS Docker instance using:
- OpenMRS Core 2.8.4
- Reference Application 3.6.0
- MariaDB 10.11.7

The dump includes 230 tables, 50 demo patients, and all module
schemas fully initialized. This enables the standalone to start
with pre-loaded demo data, bypassing the slow initialization process.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: dkayiwa