Agent Skills: megaplan

Write a "megaplan" planning notebook — a long-form Markdown doc for a multi-slice project that tracks scope, decisions, requirements, risks, and grounded research facts with cross-referenced IDs. Use when the user asks to write up a project plan, planning notebook, or "megaplan" doc, especially one spanning multiple tickets/PRs where decisions and raw research need to be preserved for later reference. Also use when bootstrapping a new megaplan from a vague idea.