Lay out the Minecraft defaults rows in two columns on wide pages

Settings > Minecraft shows each option (MinecraftPreferenceRowCard in crates/gui/ui/settings/minecraft-defaults.slint) as a stack that only widens its controls when the page is not narrow. The Workbench reference (workbench-settings-minecraft.png) lays each row out as two columns on a wide page: the text on the left (option name, "Not overridden | default ...", and the compatibility line such as "Supported" or "Unavailable: Minecraft 1.12.2 does not have this setting"), and the control with its Reset button on the right, vertically centered, so the controls line up down the page.

Scope:

• From a width the page can hold both columns, the text column and the control column sit side by side with the controls aligned to one edge across rows. Below that width the rows stack as they do now. The breakpoint is a named measurement in Theme, not a literal in markup.
• Every editor kind keeps working in the control column: toggle, slider with its readout, dropdown, window size with the keep-ratio box, text, and key binding.
• Unavailable and unverified rows keep their hatched, disabled look and their reason text; nothing moves out of keyboard order, and the Override/Reset buttons keep their tooltips and accessible names.
• Text at 90% to 125% and the CI font (DejaVu) must not overlap or clip the two columns; add a layout test at those scales for the widest editor (window size).

No change to the draft, validation, or save behavior.