docs: require warm completion before starting the app

[janicduplessis]

Description

A shell tool can return a running-job ID while worktree warming is still copying dependencies. The guide's command order alone does not tell agents to wait before starting Metro or installing packages.

Solution

Make successful warm completion an explicit prerequisite for start, platform builds, and dependency installation. Explain how to handle yielded jobs in the version-matched agent and lifecycle guides; keep the static skill router and runtime behavior unchanged.

Test plan

• Render stim guide agent and stim guide lifecycle options; verify both require warm to exit successfully and distinguish a running job from completion.
• Extend the existing guide contract test to protect the completion requirement in both entry points.

Fixes #467

[janicduplessis]

Independent review is clear at c9630bc. Reviewer independently verified all 30 guide tests and both built guide entry points. All local repository checks passed: 3,617 tests and 66 e2e tests, plus formatting, lint, build, typecheck, runtime-floor and knip.