A new app's own instructions promise a check the forge never runs #203

Pushed.

I picked the second ending: app.test stays the only place a scaffolded app's tests run, and the prose was fixed to match reality instead of adding a forge.json check.

• Reworded the README and AGENTS.md template in src/apps/scaffold.ts: instead of "the check every pull runs" / "it is the check the pull shows", they now say app.test runs beside app.run in every deploy, and the preview says live or serving · tests failed — the words a person actually sees, confirmed against the pull page.
• Left docs/APPS.md untouched — its "Checks" section already draws this distinction correctly (app's own test runs inside its deploy, concurrently with start; check is a separate, optional thing).
• Didn't add a check to the scaffold's forge.json: doing so would run bun test twice on every push for no new information, and dropping app.test instead would silently remove the "serving · tests failed" words every scaffolded preview currently gets (src/web/ui.ts's envPhrase).
• Added a test in test/apps.test.ts that runs parseCheck on the scaffolded forge.json and checks it against any sentence in the scaffolded README/AGENTS.md that mentions both "check" and "pull" — it fails on the unpatched scaffold (prose claims a check, forge.json declares none) and passes now.

bun test/bun x tsc --noEmit both pass on my changes (ran the exact test list from this repo's own forge.json check); the only 3 failures I saw are pre-existing git-auth flakiness in this sandbox, reproduced identically on unmodified main.

Closes #192