## Why

The MVP already has trace, evidence hardening, and evaluation artifacts, but the interview demo path is still too scattered. This change packages the existing capabilities into a repeatable demo runbook that can be executed and explained in a short interview window.

## What Changes

- Add a focused interview walkthrough for the payment-timeout MVP demo.
- Add reusable request payloads and PowerShell scripts under `mvp/demo`.
- Add a trace inspection checklist that maps runtime output to the engineering story.
- Keep the change documentation-only and script-only; no backend runtime behavior changes.

## Capabilities

### New Capabilities

- None.

### Modified Capabilities

- `mvp-demo-trace-acceptance`: Extend the demo acceptance surface with a repeatable interview runbook and executable local demo scripts.

## Impact

- Affects `mvp/demo` documentation and scripts.
- Adds issue and devflow tracking files.
- No Java production code, API contract, database schema, or dependency changes are expected.