docs: add a sanitized end-to-end AET handoff example

[AdvancingTitans]

Goal

Add a short, runnable example under examples/ that shows a realistic coding-agent handoff through audit → review → proof-bound trace → evidence pack.

Acceptance criteria

• Uses only synthetic or sanitized repository data.
• Includes the smallest intent contract and commands needed to reproduce the flow.
• Explains which claims are PASS, which can remain UNKNOWN, and why.
• Does not include raw command logs, tokens, private paths, or secrets.
• Links from the README or the examples directory when complete.

Why this is a good first issue

It is documentation-first, exercises the public CLI end to end, and creates a useful adoption reference without changing AET runtime behavior.