🐛 let the About page scroll so the app name and version are not squeezed out

[guiyanakuang]

Summary

The desktop About page showed only the logo above the Resources card. The app name, version line and the GitHub / X / website buttons were missing, while the mobile About page shows "CrossPaste" and "Version 2.2.1 (126800)" under the logo.

The text was never removed. The brand block took the leftover height with weight(1f), and on the 700dp main window the Resources and Support cards plus the footer left it roughly 100dp. Column measures children in order with the remaining space, so the 72dp logo and the 16dp spacer consumed it and the name, version and social row were measured down to zero height.

Change

• Make the About page scroll (verticalScroll) instead of relying on the brand block absorbing leftover space.
• Give the brand block fixed vertical padding rather than weight(1f) + centered arrangement, so it always lays out at its natural height.

No copy changes: the version line already uses AppInfo.displayVersion(), which renders the same 2.2.1 (126800) format as mobile.

Verification

• ./gradlew app:compileKotlinDesktop passes.
• Not run visually in this session because an installed CrossPaste instance was already running and holds the single-instance lock. Please confirm on the About page after pulling.