Feature: Consider supplying a static redirect

WebForms apps sometimes have a static method in each page that allow the page to be open with pre-work and then a redirect (mine do).

Consider a static redirect method in testable page.

I hacked this by supplying a StaticContext, but I think a static redirect might be better.

Start by reviewing the existing StaticContext workaround described in the issue and the testable page behavior it supports. Clarify the intended static redirect API and how pre-work should be represented; done means the expected redirect flow is defined and covered by the harness.

索引モデルが issue の本文から書いたものです。