feat: Implement AI Knowledge Sync Utilities and Event Handlers

- Added AIKnowledgeActivationStatus and AIKnowledgeSyncStatus enums to models.py for managing activation and sync states.
- Introduced AIKnowledgeSync class in aiknowledge_sync_utils.py for synchronizing CAIKnowledge entities with XAI Collections, including collection lifecycle management, document synchronization, and metadata updates.
- Created a daily cron job (aiknowledge_full_sync_cron_step.py) to perform a full sync of CAIKnowledge entities.
- Developed an event handler (aiknowledge_sync_event_step.py) to synchronize CAIKnowledge entities with XAI Collections triggered by webhooks and cron jobs.
- Implemented a webhook handler (aiknowledge_update_api_step.py) to receive updates from EspoCRM for CAIKnowledge entities and enqueue sync events.
- Enhanced xai_service.py with methods for collection management, document listing, and metadata updates.

services/espocrm.py

@@ -473,3 +473,70 @@ class EspoCRMAPI:
         except aiohttp.ClientError as e:
             self._log(f"Download failed: {e}", level='error')
             raise EspoCRMError(f"Download request failed: {e}") from e
+
+    # ========== Junction Table Operations ==========
+
+    async def get_junction_entries(
+        self,
+        junction_entity: str,
+        filter_field: str,
+        filter_value: str,
+        max_size: int = 1000
+    ) -> List[Dict[str, Any]]:
+        """
+        Load junction table entries with filtering.
+
+        Args:
+            junction_entity: Junction entity name (e.g., 'CAIKnowledgeCDokumente')
+            filter_field: Field to filter on (e.g., 'cAIKnowledgeId')
+            filter_value: Value to match
+            max_size: Maximum entries to return
+
+        Returns:
+            List of junction records with ALL additionalColumns
+
+        Example:
+            entries = await espocrm.get_junction_entries(
+                'CAIKnowledgeCDokumente',
+                'cAIKnowledgeId',
+                'kb-123'
+            )
+        """
+        self._log(f"Loading junction entries: {junction_entity} where {filter_field}={filter_value}")
+
+        result = await self.list_entities(
+            junction_entity,
+            where=[{
+                'type': 'equals',
+                'attribute': filter_field,
+                'value': filter_value
+            }],
+            max_size=max_size
+        )
+
+        entries = result.get('list', [])
+        self._log(f"✅ Loaded {len(entries)} junction entries")
+        return entries
+
+    async def update_junction_entry(
+        self,
+        junction_entity: str,
+        junction_id: str,
+        fields: Dict[str, Any]
+    ) -> None:
+        """
+        Update junction table entry.
+
+        Args:
+            junction_entity: Junction entity name
+            junction_id: Junction entry ID
+            fields: Fields to update
+
+        Example:
+            await espocrm.update_junction_entry(
+                'CAIKnowledgeCDokumente',
+                'jct-123',
+                {'syncstatus': 'synced', 'lastSync': '2026-03-11T20:00:00Z'}
+            )
+        """
+        await self.update_entity(junction_entity, junction_id, fields)