Add scenario override and improve evidence handling in mock reviews

[simonhsze]

What

Improve the document-driven review path by making scenario selection and mock evidence handling more explicit and less brittle.

Motivation

The current launch story correctly emphasizes document-driven decision review, but there are two follow-up gaps:

1. scenario detection is heuristic and can misroute some prompts
2. the mock adapter responds to supporting files via keyword-sensitive evidence checks, which is useful for demos but still brittle

Scope

• add an explicit CLI scenario override for ac debate
• surface the detected scenario in CLI output and/or debate artifacts
• review keyword-based evidence checks in adapters/mock.py
• improve mock-path behavior so attached files influence judgments more transparently and predictably
• add tests covering misrouting and override behavior

Why this matters

This would make the document-driven demo path more robust and easier to trust, especially for first-time users evaluating the project through the mock adapter.