Make the fresh-checkout demo self-contained

[itsjling]

Closes #24.

Summary

• add a one-command local demo after clean setup
• serve the checked-in fixture as JSON at the live data route
• stop retrying when the fixture is missing or malformed
• document offline use and hot reload

Verification

• npm ci
• npm run lint
• npm test (69 tests)
• npm run docs:check
• npm run docs:build
• npm run fallow:audit

Scope

This is an independent root PR. It makes no provider or remote-repository request.

Stack

1. Keep live refresh ordered and fault-tolerant #61
2. Make the fresh-checkout demo self-contained #42 👈 current
3. Add one-command live and mocked development modes #58
4. Prove one full review journey in a real browser #59

[itsjling]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Keep it up!

Reviewed commit: f6d24fc0f0

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[itsjling]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Swish!

Reviewed commit: f6d24fc0f0

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".