Add sync strategy documentation and templates for bidirectional sync between EspoCRM and Advoware

- Introduced SYNC_STRATEGY_ARCHIVE.md detailing the sync process, status values, and flow for updating entities from EspoCRM to Advoware and vice versa.
- Created SYNC_TEMPLATE.md as a guide for implementing new syncs, including field definitions, mapper examples, sync utilities, event handlers, and cron jobs.
- Added README_SYNC.md for the Beteiligte sync event handler, outlining its functionality, event subscriptions, optimizations, error handling, and performance metrics.

bitbylaw/README.md

@@ -18,6 +18,10 @@ Siehe: [docs/DEVELOPMENT.md](docs/DEVELOPMENT.md) für Details.
 1. **Advoware API Proxy** - REST-API-Proxy mit HMAC-512 Auth ([Details](steps/advoware_proxy/README.md))
 2. **Calendar Sync** - Bidirektionale Synchronisation Advoware ↔ Google ([Details](steps/advoware_cal_sync/README.md))
 3. **VMH Webhooks** - EspoCRM Webhook-Receiver für Beteiligte ([Details](steps/vmh/README.md))
+4. **Beteiligte Sync** ⭐ - Bidirektionale Synchronisation EspoCRM ↔ Advoware ([Docs](docs/BETEILIGTE_SYNC.md))
+   - Event-driven sync mit Redis distributed lock
+   - Stammdaten-Sync (Name, Rechtsform, Geburtsdatum, etc.)
+   - Template für weitere Advoware-Syncs
 
 ## Architektur