Keep the page as tall as the window while the red save bar shows

[PhilReinking]

The red save bar sat above the page and added its height to it. Now the bar and the page share one column as tall as the window, so the bar takes its space from the page. Fixes BITS-296

• Every page with a banner is affected, also the dashboard. Short pages look the same; long pages scroll as before.

Tested: page height equals window height with the bar shown at 1440, 1024 and 390 (before: +52, +52, +60 px); the editor reaches its end screen. Lint, vue-tsc, Vitest pass.

Not tested: a real failed save; I set the failed-save state by hand.

🤖 Generated with Claude Code

[PhilReinking]

OK at fe152f5. In Brave, with the red bar (also a real failed save) and the green bar, all 8 pages on this layout stay window-high at 1440, 1024 and 390; on main they were 52 to 96 px taller. The long profile page scrolls as before. In the editor, the last question and the end screen scroll into view, and the bar and Retry stay on screen. Without a bar, pages match main. CI green.

[PhilReinking]

OK at 17cb82b, CI green. Re-check of the changelog merge only: merging main conflicted only in CHANGELOG.md and changes no other file. The code diff vs main is the same as at fe152f5. The #290 line is word for word as before, 1 line added and 0 removed, last in Fixed. It merges cleanly with #287 and #289, in pairs and all 3 together. The OK at fe152f5 covers the rest.