feat(sync): Implement comprehensive sync fixes and optimizations as of February 8, 2026

- Fixed initial sync logic to respect actual timestamps, preventing unwanted overwrites.
- Introduced exponential backoff for retry logic, with auto-reset for permanently failed entities.
- Added validation checks to ensure data consistency during sync processes.
- Corrected hash calculation to only include sync-relevant communications.
- Resolved issues with empty slots ignoring user inputs and improved conflict handling.
- Enhanced handling of Var4 and Var6 entries during sync conflicts.
- Documented changes and added new fields required in EspoCRM for improved sync management.

Also added a detailed analysis of syncStatus values in EspoCRM CBeteiligte, outlining responsibilities and ensuring robust sync mechanisms.

bitbylaw/docs/INDEX.md

@@ -69,12 +69,20 @@
 
 ### 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)
+#### 📚 Main Documentation
+- **[SYNC_OVERVIEW.md](SYNC_OVERVIEW.md)** - ⭐ **START HERE** - Komplette Sync-Dokumentation
+  - System-Architektur (Defense in Depth: Webhook + Cron)
+  - Beteiligte Sync (Stammdaten): rowId-basierte Change Detection
+  - Kommunikation Sync (Phone/Email/Fax): Hash-basierte Change Detection, 6 Varianten
+  - Sync Status Management: 8 Status-Werte, Retry mit Exponential Backoff
+  - Bekannte Einschränkungen & Workarounds (Advoware API Limits)
+  - Troubleshooting Guide (Duplikate, Lock-Issues, Konflikte)
+
+#### 📁 Archive
+- **[archive/](archive/)** - Historische Analysen & Detail-Dokumentationen
+  - Original API-Analysen (Kommunikation, Adressen)
+  - Code-Reviews & Bug-Analysen
+  - Detail-Dokumentationen (vor Konsolidierung)
 
 ### Utility Scripts