Applies the same treatment to the Join tab: label and button centred on both
axes, button filling the width at 56dp tall, and the same asymmetric screen
padding. An empty state that looks different depending on which tab you are
on reads as a bug rather than as variety.
The two shared dimensions move into ui/Dimens.kt rather than being duplicated
per screen, so the tabs cannot drift apart later.
Verified on an API 37 emulator: both tabs now present an identical empty
state. 65 unit and 17 instrumented tests still pass.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
JMR-devandClaude Opus 5
e5f274183c