Preview imports the mock transport statically and wraps every story in
a fresh RegistryProvider seeded with mock mode + the story's scenario
parameter (dark default, light via toolbar). One story file per page
(Default + FirstRun/Syncing/Errors where meaningful) plus the whole
shell. tools/screenshots.mjs mirrors the console's harness: headless
Chromium over storybook-static, every Pages/* + Shell/* story.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
