Prepare workload-bounded parallel plans and short launches for 6.2.0

[mzored]

Plan review could treat a single umbrella outcome as a feasible assignment, while the generic launch instruction allowed omitted workflow invocation and repeated task or policy content. This release makes the optional plan contract assess the complete workload, prepare bounded vertical slices with genuine parallel readiness, establish a thin real path only where one is missing, and return an explicit short longrun launch by default.

Owner-selected workflows, authorization provenance, first-slice safety, mature paths, compatible migrations, uniform automation, and small cohesive changes are preserved. The kernel and execution workflows are unchanged. Eight arm-aware probes are added; all 105 existing cases survive. Version and English documentation align at compatible MINOR 6.2.0.

Validation:

• Full python scripts/check.py passed on the final candidate using a task-owned isolated temporary root and the unchanged check limits; git diff --check is clean.
• Focused corpus/preflight checks: 60 passed. Claude strict schema validation: PASS locally; the pinned Codex validator is required in CI.
• Isolated read-only Codex review: APPROVE, no qualifying findings or suggestions. Reporting-only edits record that verdict; runtime and corpus remain unchanged.
• New behavior, clean installation, activation, continuity, context fit, cost, and live parallel execution remain UNVERIFIED. No paid behavioral comparisons ran.

The release workflow will publish the separate capability matrix. The unrelated local dogfood edit is excluded.