Fix draft mode rendering with Cache Components (#100728)
PR #77141 made `'use cache'` bypass cache-handler reads and cache
persistence when draft mode is enabled. Later changes, including #98005,
made cached navigations reuse the static RDC. The additional
postponed-state lookup for self-hosted RSC navigations and Server
Actions did not check draft mode, so those renders could reuse published
values.
Draft mode HTML page loads already bypassed the response cache. Both
document and navigation responses could still generate an embedded
runtime prefetch with Partial Prefetching. Its final prerender expected
RDC entries that draft mode deliberately did not save, which caused
unexpected cache miss warnings.
This change skips the additional postponed-state lookup for draft mode
requests and disables cached-navigation rendering for their document and
navigation responses. Server Actions that enable draft mode discard the
published RDC before the subsequent render.
Dedicated runtime-prefetch requests still use their existing renderer.
PR #98533 proposes disabling client-initiated prefetches in draft mode.
That work remains separate and may continue in a replacement PR.
The tests cover fresh draft mode documents and navigations, actions that
enable and disable draft mode, and form submissions without JavaScript.
Fixes #100680
Closes #100685
Closes #100697
