Make no-progress detection failure-sensitive

[mmprotest]

Motivation

• Improve the runner’s no-progress detection so repeated failing validations are treated as progress when the failure cause changes, avoiding premature finalization.
• Make evidence signatures more discriminating by incorporating a normalized failure fingerprint derived from command output.
• Ensure file mutations, diagnostic actions, or successful write/patch operations reduce repeated-command pressure.

Description

• Add a general failure_fingerprint(stdout, stderr, exit_code) that extracts and normalizes the most informative failure line (stripping ANSI, paths, temp paths, timestamps, UUIDs, addresses, line numbers) and falls back to a compact hashed tail. (see villani_code/execution_context.py)
• Store the fingerprint on CommandRecord.failure_fingerprint and ValidationEvidence.failure_fingerprint, and compute it from command stdout/stderr when building command records.
• Extend the repeated-evidence key to include fingerprint and track repetition with an epoch-aware counter (_evidence_repetitions and _progress_epoch) so that intervening workspace mutations or new diagnostic evidence reset repetition pressure.
• Advance the progress epoch for workspace-affecting mutations and for diagnostic/tool uses (and for successful Write/Patch), so identical failures after meaningful changes are treated as progress.
• Add unit tests covering: differing tracebacks treated as progress, identical traceback triggering no-progress after threshold, file mutation resetting matching failure pressure, and normalization of volatile traceback details.

Testing

• Ran pytest -q tests/test_execution_context_isolation.py (targeted tests exercising the new logic) and all tests in that file passed.
• Ran ruff check on the modified files and it passed.
• Ran the full test suite pytest -q; the changes did not affect the targeted execution-context tests, but the full run reported 7 unrelated failures in hardening/interactive/mission/planning/TUI contract tests (these failures predate or are outside the scope of the execution-context change).

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Codex Task