Add knowledge-base resource type

[gkennos]

Motivation

oa-configurator requires a shared knowledge resource, explicitly separate from the existing DB/schema ResourceConfig

• knowledge source = where mapping guidance/conventions can be retrieved from
• kind = how it is backed
• examples of kind: filesystem_packs, package_data, rag_index, maybe later hybrid

Pitch

example:

[knowledge_resources.core_packs]
kind = "filesystem_packs"
root = "/opt/omop/knowledge/packs"

[knowledge_resources.guidance_rag]
kind = "rag_index"
backend = "pgvector"
resource = "emb_db"
collection = "omop-guidance"

Alternatives

No response

Additional context

Initial goal is that groundworkers can ask for a resolved knowledge source and branches by capability, not by package name.