New check self_contradiction: flag verdicts contradicting their own evidence

[royalpinto007]

Problem

Observed failure: "no open security issues" above a pasted list of issues; "all tests passed" next to a traceback.

Pattern

Add a check in agentrace/checks.py (sibling: check_absence_as_evidence, regex + _context() snippet); test via _run(result=...). Fire self_contradiction (medium) on co-occurrence of a zero/absence claim ("none found", "no X", "all passed") with enumerated counter-evidence (numbered items, tables, tracebacks) in the same result.

Acceptance

New check self_contradiction. _run(result="No open issues:\n1. #12 ...\n2. #14 ...") flagged; plain "none found" with no list clean.

[Rayan-and-beyond]

I'd like to work on this. I'll add the self_contradiction check and focused regression coverage.

[github-actions]

It's yours, @Rayan-and-beyond. Marked this as claimed.

Take your time, and shout in this thread if you get stuck. If there's no activity for 14 days the claim is released so someone else can pick it up.