Dialog completeness: every per-terminal config option is now editable
in the terminal tables.

- A Bonded checkbox per row (the config's "bonded" key, previously
  file-only and shown as a text suffix): checked, the terminal's
  contacts short into one internally joined lug - the total value
  stays prescribed, the per-contact split becomes a solve outcome.
  Same-name rectangle groups seed it checked (unchanged default);
  unchecking one falls back to the per-cell area share, and checking
  a single-contact terminal gives it an equipotential-lug contact
  instead of uniform injection. Save config... writes the flag back
  (removed when unchecked - false is the schema default).