Reconcile v0.9.0 external closure

[xeonvs]

Goal

Reconcile repository truth after completed stable v0.9.0 publication. The archived v0.9.0 plan still said external stable delivery pending, although the immutable Release, tag, Actions receipts, issue closure, milestone closure, branch cleanup, and synchronized main already existed.

This is a no-release documentation/process correction in the same PR. It does not modify toolkit runtime, package or next-release versions, OCR compatibility, dependencies, workflows, tags, Release assets, registry artifacts, attestations, provenance, or the immutable receipt.

Delivered

1. Records the exact external v0.9.0 closure evidence in the current archived plan and index.
2. Adds .release-reconciled-version=0.9.0 as the single machine-readable external-closure marker.
3. Defines two valid lifecycle states: a release PR has a newer .release-version and a pending current archive section; its post-publication no-release closure PR aligns both markers and completes that section.
4. Adds one focused existing-suite contract for marker, current archive status, and index consistency.
5. Returns PLANS.md to its inactive template after validation and self-review.

Validation

• uv run pytest -q tests/test_operations_docs.py — 30 passed
• uv run pytest -q tests/test_distribution_contents.py tests/test_release_authorization.py — 26 passed
• focused Ruff check and format check
• git diff --check
• ./scripts/gitleaks.sh origin/main HEAD
• complete range self-review; no runtime/package/workflow changes

External evidence already read back

• Release PR Release v0.9.0 #173 merge and annotated v0.9.0 target: 39ff90a5eb58072f4a5ef5ea6657ba4cadbe1bb0
• Stable workflow: #33734006965, successful
• Immutable GitHub Release: v0.9.0
• Release receipt SHA-256: 1cc0d0641ea76675f403084c21e0f35b97c611e1ea11ea8328d3af7de6236857
• Issues [Bug]: Pre-execution status posting ignores the CI_COMMIT_SHA fallback #167, [Feature]: Add an explicit limited mode for unprotected GitLab target branches #168, [Bug]: Receipt v6 can reject a toolkit-finalized review when evidence action counts diverge #169, [OCR compatibility] Qualify v1.11.2 #170, and [OCR compatibility] Qualify v1.11.3 #172: closed by GitHub Actions receipts
• Milestone Release v0.2.0 #11 v0.9.0: closed with 0 open / 5 closed
• main == origin/main == v0.9.0^{} at stable release closure; release branch deleted

No closing keywords are used; the release issues are already closed.