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/docs/INDEX.md

@@ -46,16 +46,35 @@
 - [calendar_sync_all_step.md](../steps/advoware_cal_sync/calendar_sync_all_step.md) - Employee cascade
 - [calendar_sync_event_step.md](../steps/advoware_cal_sync/calendar_sync_event_step.md) - Per-employee sync (complex)
 
-**VMH Webhooks** ([Module README](../steps/vmh/README.md)):
-- [beteiligte_create_api_step.md](../steps/vmh/webhook/beteiligte_create_api_step.md) - Create webhook
+**VMH Webhooks & Sync** ([Module README](../steps/vmh/README.md)):
+- **Beteiligte Sync** (Bidirectional EspoCRM ↔ Advoware)
+  - [BETEILIGTE_SYNC.md](BETEILIGTE_SYNC.md) - Complete documentation
+  - [README_SYNC.md](../steps/vmh/README_SYNC.md) - Event handler docs
+  - [beteiligte_sync_event_step.py](../steps/vmh/beteiligte_sync_event_step.py) - Event handler
+  - [beteiligte_sync_cron_step.py](../steps/vmh/beteiligte_sync_cron_step.py) - Cron job
+- **Webhooks**
+  - [beteiligte_create_api_step.md](../steps/vmh/webhook/beteiligte_create_api_step.md) - Create webhook
 - [beteiligte_update_api_step.md](../steps/vmh/webhook/beteiligte_update_api_step.md) - Update webhook (similar)
 - [beteiligte_delete_api_step.md](../steps/vmh/webhook/beteiligte_delete_api_step.md) - Delete webhook (similar)
 - [beteiligte_sync_event_step.md](../steps/vmh/beteiligte_sync_event_step.md) - Sync handler (placeholder)
 
 ### Services
 
-- [Advoware Service](../services/ADVOWARE_SERVICE.md) - API Client mit HMAC-512 Auth
-- [Advoware API Swagger](advoware/advoware_api_swagger.json) - Vollständige API-Dokumentation (JSON)
+- **Advoware Service** ([ADVOWARE_SERVICE.md](../services/ADVOWARE_SERVICE.md)) - API Client mit HMAC-512 Auth
+- **Advoware API Swagger** ([advoware_api_swagger.json](advoware/advoware_api_swagger.json)) - Vollständige API-Dokumentation
+- **EspoCRM Service** ([espocrm.py](../services/espocrm.py)) - EspoCRM API Client mit X-Api-Key Auth
+- **Sync Services**
+  - [beteiligte_sync_utils.py](../services/beteiligte_sync_utils.py) - Sync utilities (lock, timestamp, merge)
+  - [espocrm_mapper.py](../services/espocrm_mapper.py) - Entity mapping EspoCRM ↔ Advoware
+
+### Sync Documentation
+
+- **[BETEILIGTE_SYNC.md](BETEILIGTE_SYNC.md)** - Complete sync documentation
+  - Architecture, data flow, troubleshooting
+- **[SYNC_TEMPLATE.md](SYNC_TEMPLATE.md)** - Template für neue Advoware-Syncs
+  - Best practices, code templates, architecture principles
+- **[ENTITY_MAPPING_CBeteiligte_Advoware.md](ENTITY_MAPPING_CBeteiligte_Advoware.md)** - Field mapping details
+- **[SYNC_STRATEGY_ARCHIVE.md](SYNC_STRATEGY_ARCHIVE.md)** - Original strategy analysis (archived)
 
 ### Utility Scripts
 
@@ -77,15 +96,21 @@ docs/
 ├── DEVELOPMENT.md            # Development guide
 ├── GOOGLE_SETUP.md           # Google Calendar setup
 ├── TROUBLESHOOTING.md        # Debugging guide
+├── BETEILIGTE_SYNC.md        # ⭐ Beteiligte sync docs
+├── SYNC_TEMPLATE.md          # ⭐ Template for new syncs
+├── ENTITY_MAPPING_CBeteiligte_Advoware.md  # Field mappings
 └── advoware/
     └── advoware_api_swagger.json  # Advoware API spec
 
 steps/{module}/
 ├── README.md                 # Module overview
+├── README_SYNC.md            # ⭐ Sync handler docs (VMH)
 └── {step_name}.md            # Step documentation
 
 services/
-└── {service_name}.md         # Service documentation
+├── {service_name}.md         # Service documentation
+├── beteiligte_sync_utils.py  # ⭐ Sync utilities
+└── espocrm_mapper.py         # ⭐ Entity mapper
 
 scripts/{category}/
 ├── README.md                 # Script documentation