Add community.knowledge-rag — Local RAG with hybrid search + reranking

[lyonzin]

Summary

Adds two server definitions for knowledge-rag — a local RAG system built for Claude Code.

• community.knowledge-rag-uvx — runs via uvx knowledge-rag (PyPI)
• community.knowledge-rag-npx — runs via npx -y knowledge-rag (npm)

About the server

knowledge-rag is a fully local MCP server providing retrieval-augmented generation for Claude Code:

• Hybrid search: semantic (FastEmbed BAAI/bge-small-en-v1.5 384D ONNX) + BM25 inverted-index (128× speedup) + RRF fusion
• Cross-encoder reranking: Xenova/ms-marco-MiniLM-L-6-v2 (lazy-loaded)
• 13 MCP tools: search_knowledge, get_document, search_similar, add_document, add_from_url, update_document, remove_document, reindex_documents, get_reindex_status, list_categories, list_documents, get_index_stats, evaluate_retrieval
• 20 format parsers: markdown, PDF, DOCX, code, JSON, CSV, and more
• Async background reindex with file watcher (watchdog)
• GPU CUDA 12 support with CPU fallback
• Zero external servers: everything runs locally (ChromaDB embedded)

Stats

• PyPI: pip install knowledge-rag — 15.9K+ downloads
• npm: npx -y knowledge-rag
• MIT license
• 70+ enterprise users

PR Checklist

• $schema points to ../schemas/server-definition.schema.json
• id follows {tld}.{name}-{transport} pattern and is unique
• name is human-readable
• schema_version is "2.1"
• transport.type is "stdio"
• auth.type is "none" (fully local, no API keys)
• contributor fields filled
• links.repository and links.documentation present
• platforms set to ["all"]
• capabilities accurately reflects the server
• metadata.inputs is [] (no required user inputs)
• Commit signed off (Signed-off-by) per DCO requirement
• No sensitive data in definition files

Closes #96