Help with running embedded with S3 Sync

**What would you like to be added or enhanced**

I'm trying to understand how to run in embedded mode with S3 storage sync. Haven't found any examples in doc and been trying to understand the codebase for it, but it's been hard. I've managed to get the store to work locally and managed to create an S3 Remote Storage but haven't found how to plug em.

**Why is this needed**

To run immudb embedded with S3 sync.

**Additional context**

The issue mentions embedded mode, a local store, S3 Remote Storage, and S3 sync, but names no files, tests, or entry points. Start by tracing how embedded storage and remote-storage configuration connect, then document a working S3-sync setup with clear prerequisites and verification steps.

Written by the indexing model from the issue text.