v0.8.48 — a spelling is exact, so it must not be gated behind a similarity score

Fixed

• A spelling variant could register as a new project or section whenever it
  also scored below the similarity floor. The guard that refuses a name
  differing from a registered one only in separators or capitalisation was
  applied to the TRIGRAM NEIGHBOURS a confusable query returned — which quietly
  made an exact rule conditional on a fuzzy one. Measured on the live registry:
  testing versus Test_Ing scores 0.545 against a floor of 0.6, so the
  variant never reached the check and registered as a brand-new value. This was
  latent in the project registry from v0.8.44 and was reproduced on the domain
  registry the day it shipped: Shared_Memory_Monitor is now refused against the
  registered shared-memory-monitor, and was not before.

  The spelling check now runs over every registered name, ahead of the
  confusable query, through one shared pure helper both axes call. The floor was
  deliberately not lowered: that would flatten two populations it exists to
  separate — legitimately distinct names sit just under it — and would train the
  reflex to override a warning that fires on correct input. The two gates answer
  different questions and run in order: a SPELLING is exact equality on a
  normalised key and cannot be confirmed away; a CONFUSABLE is a fuzzy neighbour
  the operator may confirm as genuinely distinct. Both error codes are unchanged.

• save_decision --domain was parsed and dropped on the floor. The flag
  reached the argument parser and nothing threaded it into the record, so a
  decision fell back to inheriting its evidence's sections. It read as correct
  because the inherited answer happened to match what had been asked for — the
  edge carried asserted_by='inherited' where an assertion should have been
  bare. Now packed into the decision blob, beside project, which is the half
  the gateway resolves a judgement's axes from. vector-skill.py's
  save_decision gains the same parameter, so the two front doors stay at parity.

  The regression tests assert the provenance of the edge, not just the
  presence of a section name: a decision whose evidence sits in the same section
  produces the same name either way, and only the stamp tells an assertion from
  a default.

Notes

• A live probe over the registries found no existing pair of projects, and no
  pair of sections within one project, sharing a spelling key — so the defect
  registered nothing before it was caught beyond the one probe value, which was
  retired.