[eagleoflqj]

Prevent the check and retry buttons from changing size when their labels switch to “Checking…”, which previously moved adjacent controls in both English and Simplified Chinese.

Add a reusable StableSizeView that lays out all supplied states in a ZStack and displays only the selected state. Inactive states reserve space while remaining unavailable to hit testing and accessibility. Share SimulatorCheckButton across all three discovery/setup views, with each title literal defined once and reused for both display and sizing.

Validation:

• Release build, strict Swift formatting, and all six CTest checks passed.
• Native geometry regression test passed 16 combinations covering both languages, check/retry labels, regular/large controls, and 14/24-point fonts. It checks both button bounds and the neighboring button's position.
• A temporary implementation without reserved space fails that regression test on the first case.
• Compiler string extraction preserves the existing localization catalog without changes.