Fix Go recovery, gate routing, evidence, and handoff defects

[boshu2]

What

Repair 13 audited Go CLI defects across doctor recovery, gate routing, evidence ingestion, and session handoffs. Doctor preserves recoverable snapshots and reports unresolved findings; gates retain exact changed-file scope and advisory semantics; malformed evidence fails closed; handoffs report observed Git state and chronological recency.

Why

These failures could overwrite recovery data, skip required checks, admit malformed evidence, or restore stale context. Each defect has a regression witness. Existing skill contracts remain unchanged for this bounded workflow evaluation.

How I tested

• Regression witnesses failed before repair and pass after repair.
• Combined Go build, vet, race/shuffle tests with coverage, coverage floor, pinned lint, and complexity checks pass.
• Generated projections are current; local aggregate reports 10 passed, 0 failed, 1 optional skip.
• All 52 selected gates pass. Authoritative Linux/Windows correctness, security, full registry, and installation CI pass.
• Fresh author-distinct OpenAI/Codex review verified all 13 repairs and all 33 changed paths on 84029ee533be0a73ac6c882eb9cf7369d52a0055, including independent critical race regressions; no findings or unchecked acceptance.
• Directory reverse moves retain the existing advisory-lock concurrency boundary; this does not claim exhaustive hostile filesystem-race coverage.

Checklist

• Go build and tests pass, including race detection
• No secrets or credentials added
• Compatibility behavior documented in the changed contract where applicable