Exports the standard nav functions as vi.fn() and a beforeNavigate that
captures the registered callback. The exported simulateNavigate(href)
helper fires that callback and returns the cancel spy — the whole
capture-and-fire pattern lives in the shared module, not the raw callback.
An embedded beforeEach clears the captured callback and the mock call
histories before every test. Part of #560.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Single home for the non-trivial form-interceptor enhance() shared by the
four complex consumers: it intercepts submit, invokes the SubmitFunction,
and fires the returned callback with a configurable result. setFormResult()
drives the success/failure branch; an embedded beforeEach resets it before
every test so isolation is structural. Consumed via vi.mock('$app/forms',
() => ({ ...formsMock })) through the $mocks alias. Part of #560.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
