Six tests for ThreadDetailScreen:
- empty thread shows placeholder message
- sender name rendered in card
- last email is expanded by default (reply/delete buttons visible)
- tapping expanded card collapses it
- flagged email shows star icon
- expanded card renders plain text body
Six tests for SearchScreen:
- placeholder shown when field is empty
- typing fewer than 3 characters keeps placeholder (no search fires)
- search returning empty shows "No results"
- email results shown under "Messages" section
- folder results shown under "Folders" section
- clear button resets results to placeholder
Also adds ThreadDetailScreen route to the shared test router in
helpers.dart so tests can navigate to it by URL.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
