Align v0.2.2 candidate provenance

[YuzeJ21]

What changed

• correct the v0.2.2 candidate provenance note so its 2026-07-20 isolated artifact snapshot remains historical while later merged documentation and repository-contract maintenance are identified separately
• record PR Make alpha quickstart install self-contained #172's self-contained public-alpha participant install path in the Unreleased changelog while keeping installation pinned to the verified public v0.2.1 wheel
• add fail-closed repository contracts binding the historical snapshot, current-HEAD CI separation, public-install boundary, engineering-evidence boundary, and no-Stage-1-credit wording

Why

The candidate record still described later work as local-only after those documentation and contract changes had merged. The changelog also omitted the participant quickstart improvement. This aligns the release record without publishing v0.2.2 or changing product behavior.

Evidence boundary

These checks are engineering evidence only. They do not publish v0.2.2, advance Stage 1, prove runtime correctness for a public PR, or establish customer or market validation.

Verification

• uv run pytest -q --cov=scopeproof_core --cov=apps --cov-report=term-missing:skip-covered --cov-fail-under=95 — 1,005 passed, 1 skipped, 95.84% coverage
• uv run ruff check . — passed
• uv run scopeproof benchmark — 12 cases, zero mismatches, zero must-have False Ready
• uv run scopeproof comparison-benchmark — 2 cases, zero mismatches, including Unchanged
• focused mutation checks demonstrated both stale provenance and reversed changelog evidence boundaries fail closed
• git diff --check origin/main..HEAD — clean

No release, tag, issue/PR comment, paid API, billing, private repository, fork test, outreach, or participant-validation claim is included.