[Feature Request] Exclude Inbox documents as reference examples for AI metadata suggestions while keeping full RAG indexing

Description Description I would like to suggest an optional feature that allows Paperless-ngx to exclude documents marked with an Inbox tag from the reference documents used to generate AI metadata suggestions. Important: This is not a request to exclude Inbox documents from the LLM vector index itself. All documents should remain indexed and available for semantic search, similar-document search, and document chat. The requested filtering should apply specifically to the retrieval of reference examples and taxonomy candidates used for AI-assisted metadata classification. Current situation I am running Paperless-ngx 3.4.0 with an OpenAI-compatible LLM backend and preparing to use embeddings for RAG-assisted classification. My document archive currently contains: • 4,857 documents in total • 2,954 documents considered reviewed and correctly classified • 1,903 documents marked as Inbox, awaiting review or correction • Approximately 195 co…