Execute-family controller recipe

One home for controller steps and runtime state shared across build-in-waves, build-by-story, and build-inline. Task dispatch/review lives in task-lifecycle.md beside this file. Load when that skill's Setup or After-last says to. Registered so npx skills add copies it with the execute family.

Session preflight

Three questions, before any dispatch, any isolate-workspace / git worktree add, and any first production edit: