Teach profiles and bounded framework comparisons #115

Affected library: backtest
Current version: 0.1.8
Location: profiles and parity tutorial

Problem

Named profiles are documented, but a reader lacks a runnable comparison that isolates one execution assumption and states exactly what a framework comparison proves.

Required outcome

Compare named profiles or explicit settings on frozen shared data. Explain supported comparison boundaries using retained validation evidence and link to the book's framework-comparison material. The public example must run without a licensed comparison engine.

Acceptance criteria

• The offline installed-wheel example produces the displayed differences from declared settings.
• Every parity statement names its supported workload and configuration; unsupported comparisons are labeled.
• Installed-wheel checks, applicable validation checks, and the strict MkDocs build pass.

Depends on the shared tutorial inputs and the order-timing tutorial.