Show two distinct tamper signatures in the run checker

[aruintelligence]

What changed

• Add a second one-byte source mutation beside the saved gate-claim flip. Each probe starts from the captured record, and visitors can switch between them or restore it.
• Show the exact changed JSON field or added LF byte, plus the three current check outcomes in a compact result panel.
• Keep all mutations local and preserve the checker’s unsigned self-check boundary.

Verification

• node --test test/*.test.js (9 test files passed)
• node --check docs/check-run.js
• Published captured example yields PASS/PASS/FAIL for the gate claim and FAIL/PASS/PASS for the LF byte; compiler decisions are identical after the LF edit.
• HTML IDs unique.