[Feature Request]: GraphDB

### Describe the problem

To add a GraphDB component (RDF, Tripple-Store, ...) could help, e.g. with GraphRAG and other representation of data. Something like pgvector or Apache AGE plus querying via Sparql, Cypher, ...

### Describe the proposed solution

Adding table for representation of RDF / Tripple data (Objects, edges, ...)and the necessary API extensions and query interfaces

### Alternatives considered

Installation of another DB (Neo4j, postgresql with extensions, ...) would work but wouldn't be a clean solution

### Importance

would make my life easier

### Additional Information

_No response_

The issue names no files or tests. Start by mapping the existing database component and API entry points, then compare the proposed RDF/triple-store tables with the requested SPARQL and Cypher query interfaces. Done would require an agreed scope and design for the GraphDB component; the current request does not define implementation-level acceptance criteria.

Written by the indexing model from the issue text.