Preserve UCF evidence and failure records before workspace cleanup

[sinethxyz]

Purpose

A bounded reliability pass before converging the historical RunEngine onto the UCF runtime. The previous adapter persisted a patch checksum but not the actual patch, then removed its worktree. Exceptions also bypassed outcome journaling.

Changes

• Persist plans before implementation, independently captured Git patches, complete verification/review reports, and retrievable evidence references.
• Capture tracked edits/deletions and non-ignored additions, including binaries and literal filenames, using a temporary index that leaves the actual index untouched.
• Freshly observe state even when a prior snapshot is supplied; reject stale or cross-environment state and detect mutations during verification.
• Journal failed/cancelled operations with phase and exception type, retain partial work, and preserve the primary exception if journaling also fails.
• Journal normal decisions before cleanup; record cleanup warnings separately from the verification verdict.
• Use atomic local artifact replacement and add journal reload support.
• Add 30 focused tests, including actual Git patch replay after cleanup and a fresh-process journal reload followed by a second real file-backed transition.
• Expand CI coverage and limit duplicate workflow runs.

Verified validation

GitHub Actions run 36138567006 completed successfully for head 8a421e54c5b60b209383146c5c6899369f69eaa7 against main 2639b8ebeeb485950a8faed17491b03ff440b354 on Python 3.12.14:

• Editable install: passed.
• Python compilation: passed.
• Targeted Ruff checks: passed.
• Foundation/adapter/integrity subset: 51 passed in 1.33 seconds.
• Full repository regression suite: 525 passed, 2774 warnings in 8.10 seconds.

The 51 targeted tests are included in the 525 total, not additional. This PR adds 30 tests over the previous 495-test baseline. The existing warnings remain: datetime.utcnow deprecations and three unawaited AsyncMock warnings in legacy verification tests; this PR does not claim warning-free validation.

The 30 new focused tests also passed locally on Python 3.13. Local validation used the available focused module set rather than a full dependency install; GitHub Actions provides the full actual-repository validation.

Model and verifier behavior in the new tests is deterministic test code, not live LLM validation. Git operations, worktree cleanup, artifact storage, patch replay and fresh-process journal reload are real. No paid model calls or production deployment were performed.

Explicit boundaries

See docs/evidence-retention.md. This is not crash-resume, exactly-once execution, comprehensive verifier coverage, production readiness, or adoption/deployment of worktree changes. The historical base_ref/HEAD limitation and advisory REQUEST_CHANGES policy remain documented blockers for later runtime convergence. The historical RunEngine is not migrated in this PR. No historical commits are rewritten.

Status: ready for review with green CI; left open and unmerged. Main remains unchanged by this pass.