ETS-backed knowledge base store implementation.

Uses four unnamed ETS tables (documents, entries, links, slugs) so multiple instances can coexist. Text search uses String.jaro_distance/2 for fuzzy matching on entry content and title.

Ownership & lifetime (read before "fixing" the :public tables)

This store is intentionally ephemeral and run-scoped. init/1 returns the table references inside state, which the caller threads through ctx.deps for the life of a knowledge-base session — there is no global registration and no supervised owner. When the process holding state exits, ETS reclaims the tables; that is the designed lifetime, not a leak. Persistence across runs is the job of a different Nous.KnowledgeBase.Store implementation, not this one.

The tables are :public on purpose: a single KB session is driven from several processes (the agent loop plus tool-execution tasks all receive the same state and read/write it), so a :protected table — writable only by the process that called init/1 — would break those cross-process writes. Access is gated by possession of the table reference, which never leaves the session's ctx, rather than by an ETS access mode.

Writes (e.g. store_entry/2) are sequences of individual ETS operations, not transactions. Operation order is chosen so a torn write degrades safely (a stale slug → a miss), but if you need cross-write atomicity, route writes through a serializing owner process instead of using this store directly.