Review/optimize checklist, executive-summary format, build executor (T02-T04)

docs/review-optimize-checklist.md: six checks (naming, TTL/scoping,
redundancy, compaction, ease of use, posture), applied for real to the
rein-openweights plan's section 4 -- including a genuinely useful
finding (credentials.py already expects this exact path/delivery shape,
zero code changes needed to consume it).

docs/executive-summary-format.md: six fixed fields, no bao syntax, no
restating earlier sections, explicit approve/reject/revise decision.
Rendered for real into the plan's section 5 -- ready for an actual
decision.

src/ops_mason/{plan,executor,audit}.py: the phase-4 build executor for
credential_type openbao-approle-kv. Refuses to run against anything but
an approved plan -- verified the refusal never even calls subprocess.run.
role_id/secret_id (the AppRole's own access credential, not the
downstream secret) land as 0600 files, never logged; the HCL policy
goes over stdin, never argv; the audit trail is metadata-only. 12 tests,
all mocked at the bao boundary (no live OpenBao access from this
session).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

tests/test_plan.py

@@ -0,0 +1,51 @@
+import pytest
+
+from ops_mason.plan import ConstructionPlan, PlanError
+
+
+def _write(tmp_path, frontmatter: str, body: str = "\n# Plan\n") -> str:
+    p = tmp_path / "plan.md"
+    p.write_text(f"---\n{frontmatter}\n---\n{body}")
+    return str(p)
+
+
+def test_load_parses_frontmatter(tmp_path) -> None:
+    path = _write(
+        tmp_path,
+        "id: test-plan\nstatus: draft\ndemand_source: x\nconsumer_repo: y\ncredential_type: openbao-approle-kv",
+    )
+    plan = ConstructionPlan.load(path)
+    assert plan.id == "test-plan"
+    assert plan.status == "draft"
+    assert plan.consumer_repo == "y"
+
+
+def test_is_approved_false_when_draft(tmp_path) -> None:
+    path = _write(tmp_path, "id: p\nstatus: draft")
+    assert ConstructionPlan.load(path).is_approved() is False
+
+
+def test_is_approved_false_when_approved_but_missing_approver(tmp_path) -> None:
+    path = _write(tmp_path, "id: p\nstatus: approved")
+    assert ConstructionPlan.load(path).is_approved() is False
+
+
+def test_is_approved_true_when_fully_approved(tmp_path) -> None:
+    path = _write(
+        tmp_path,
+        'id: p\nstatus: approved\napproved_by: "bernd"\napproved_at: "2026-07-27"',
+    )
+    assert ConstructionPlan.load(path).is_approved() is True
+
+
+def test_missing_frontmatter_raises(tmp_path) -> None:
+    p = tmp_path / "plan.md"
+    p.write_text("# no frontmatter here\n")
+    with pytest.raises(PlanError, match="missing YAML frontmatter"):
+        ConstructionPlan.load(str(p))
+
+
+def test_missing_required_field_raises(tmp_path) -> None:
+    path = _write(tmp_path, "id: p\n# status omitted")
+    with pytest.raises(PlanError, match="missing field"):
+        ConstructionPlan.load(path)