fix(framework): audit-prompt hardening — enforce independence + surface output contract (#261)

[montfort]

Closes #261.

Two prompt-design hardening fixes surfaced by a real 5-auditor cross-family cycle. Neither is a CLI mechanics bug — both are template gaps that let auditors drift from the intended discipline. Folded into the shipped template (and the review skill) so they persist across --prepare regenerations.

Problem A — auditor independence was not enforced

Sequential audits share .straymark/audits/<charter>/, so a later auditor can read the earlier report-*.md. In the observed cycle, the last auditor produced a meta-consolidation of the four prior reports ("I independently verified all N findings from the prior audit" + a comparison table) instead of an independent audit. Its "convergence" was copied, not independent — which silently inflates both its rating and the consolidated review's confidence.

• audit-prompts/audit-prompt.md (EN + ES): the ABSOLUTE RULE now forbids reading/grepping/referencing any other auditor's report-*.md (this Charter or any other). "Your role" and the contradictory "DO NOT ignore prior-audits folders" bullet were reworded — a sibling report may already be on disk; you must not open it.
• straymark-audit-review (all 4 runtime copies): a contamination guard in the read-reports step detects reports that reference siblings (another report-*.md, a cross-auditor comparison table, "I verified all N findings from the prior audit") and excludes them from the convergence/dedup math and the auditor rating. A prompt rule is weak — verify at review time too.

Problem B — the output contract was buried

The required frontmatter sits in the last ~170 lines of a ~3,900-line resolved prompt; by then the auditor has patterned its mental model on the embedded AILOGs (a different frontmatter), and drifts off-schema.

• New "Output contract (read this first)" block immediately after the ABSOLUTE RULE: the exact required frontmatter, the four finding categories, and an explicit "DELIBERATELY DIFFERENT from the AILOG/AIDEC frontmatter" disambiguation — with a pointer to the full §Output format at the end. A "Frontmatter note" was also added beside the embedded AILOGs.
• Note: the finding categories were already defined before the output format in this template, so the reorder the issue contemplated wasn't needed — the burial (not the order) was the real problem.

Verification

EN + ES template edits mirrored. All audit tests green: skill 12, template 9, charter_audit 21, audit 9. No CLI mechanics changed — placeholders intact, schema validation untouched.

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