Autonomous migration mode: an app from the platform gets a crew whose standing job is parity, shown as a checklist #644

Pillar: P4 Forge in a link (#590), under Just go forge (#643). One run, fresh from main. Planned: held until the owner sends the crew (#642).

Outcome. An app brought from an origin can be set to autonomous migration: its crew first writes a parity checklist against the original, then works it down, and the app's page shows progress as a plain checklist.

Today. actions/migrate.ts clones an origin repository for good and, with a crew asked for, makes it an app and tells the crew once "make it run here, adapting rather than rewriting". Nothing tracks parity or keeps the direction standing.

The path: the owner, from the platform inventory (#M3) or the migrate page, picks an app to bring over; primary action Bring it over (migration mode); next the app page's checklist.

Acceptance.

• [ ] A per-app mode migration (beside fork and autonomous): the app's crew direction becomes "run natively here with parity to <origin URL>"; its first run writes MIGRATION.md (a checklist: routes, data, auth, jobs, domains) and opens one issue per unchecked line.
• [ ] The app page shows the checklist with done/total; when all are checked the mode reads "at parity" and asks the owner to cut over (#M5).
• [ ] Selectable at spawn time next to "fork of mine" and "autonomous" (#M6 carries it in the config).
• [ ] Minimal, not bare: one primary next action; looks of the path at phone and desktop widths on the pull.

Done means reachable:

• Page: the app page's migration checklist
• MCP: apps returns the mode and progress; migrate {repo, mode:"migration"}
• Test: mode sets the direction; checklist parses; progress counts
• Look: an app mid-migration

Removes / says what it removes: the one-off "make it run here" tell in migrate.ts becomes the standing mode; say so.

Start from: src/actions/migrate.ts, src/origins/jobs.ts, src/web/pages/migrate.ts, src/web/studio/app.ts, docs/ORIGINS.md, docs/EXTRACT.md.

Must not touch: the release workflow, the chart, the old platform's repositories (read only).

First real use: the owner's home-maintenance import (#617). #617 is with mason now, so it was not steered; when this mode lands, switch home-maintenance into it.

Live triage (automatic, not written by a person): filed under P4 Forge in a link, which it names.