New page (execution/outcomes.mdx) defines the 5 stage statuses, documents
how each handler produces them, and explains allow_partial, auto_status,
the retry loop, goal gate interaction, and outcome in edge conditions.
Existing pages updated: added missing `skipped` status to outcome key
descriptions, improved `goal_gate`/`auto_status` descriptions in the
dot-language reference, added `allow_partial` to the attributes table,
and added cross-links from failures.mdx and transitions.mdx.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
