feat(unic-archon-dlc): /build repairs what its precheck finds before it reports a verdict #659

Problem

After #483, a /build run whose precheck reports a hard finding ends fail and opens no pull
request. The finding is often small and local, and a human has to start a new run to fix it.

Idea

A bounded fix loop between implement-review-precheck and evidence: fix the hard findings, then
run the precheck again, up to a configured number of attempts. When the attempts run out, #483's
verdict applies unchanged.

Constraints already known

• A finding is never marked fixed because a later precheck stopped mentioning it. That is
  #482's defect, and a review omits findings on identical code (#501 measures how often).
  "Fixed" must derive from an artefact, such as the cited file changing between two recorded heads.
• A fix must not weaken the test that proves a criterion. The RED/GREEN anti-cheat record in
  build-state.json does not cover changes made after the loop, so the fix pass needs its own record.
• It changes what /build produces, so it lands after run 4 on #498, never inside it.

Depends on

• #483: the verdict for the case where the attempts run out.
• #482: the rule for what counts as fixed.

Filed 2026-10-27 from the grilling of #483, where the maintainer ruled the loop out of that ticket. needs-triage: grill before specs.