v0.8.21

Changed

• /discover selects injected knowledge precision-first: fusion of full-text,
  name and semantic hits, token matching restricted to words in entity names
  instead of substrings anywhere, and semantic recall only from two keywords on.
  When no source contributes anything, nothing is injected instead of the three
  least unsuitable entries. Measured against 40 real session prompts, the share of
  relevant injections rose from ~25% to ~75%. (#92)