Pull latest entities to the graph

Adds documents to a graph by copying their entities and relationships.

This endpoint:

1. Copies document entities to the graphs_entities table
2. Copies document relationships to the graphs_relationships table
3. Associates the documents with the graph

When a document is added:

• Its entities and relationships are copied to graph-specific tables
• Existing entities/relationships are updated by merging their properties
• The document ID is recorded in the graph’s document_ids array

Documents added to a graph will contribute their knowledge to:

• Graph analysis and querying
• Community detection
• Knowledge graph enrichment

The user must have access to both the graph and the documents being added.