move LLM-dependent modules into agents/ subdir
Separate the agent layer (everything that calls external LLMs or
orchestrates sequences of such calls) from core graph infrastructure.
agents/: llm, prompts, audit, consolidate, knowledge, enrich,
fact_mine, digest, daemon
Root: store/, graph, spectral, search, similarity, lookups, query,
config, util, migrate, neuro/ (scoring + rewrite)
Re-exports at crate root preserve backwards compatibility so
`crate::llm`, `crate::digest` etc. continue to work.
cee9b76a7b