[thesiti92]

On Windows and Linux the window controls sit over the right end of the top row, and nothing in the canvas made room for them. The tour's close button, in the right-hand column and in a fullscreen tour, sat under them, so it could only be closed with Escape. The board's page bar lost its Discord, Report a bug, Diff settings and More buttons the same way.

Fixes #1490.

Changes

• Desktop publishes --review-window-controls-end on the editor and Ask parts: how far the titlebar's right cluster overlaps each part. It reuses the titlebar's zoom-aware width, so it holds at any zoom. It is 0 on macOS, and 0 on the editor part while the right column sits between it and the controls.
• The page bar, the right-column header and fullscreen headers pad by it. Only the column that reaches the window's top-right corner does; a fullscreen tour's left column, and a flow tour's panel stacked under its stage, keep their padding.
• Fullscreen header rows (tours, expanded diagrams, the software map) are now page-bar height (40px), so their rule meets the bottom of the window controls. On macOS they grow from 35/36px to 40px too. Inline diagram headers are unchanged.

Testing

• Windows 11 (Parallels) with this branch's canvas and host change applied to 0.5.1: the page bar, the side tour and the fullscreen tour clear the controls at 100% and 120% zoom and in a narrow window; both close buttons work with real clicks.
• Not run: Linux, and a narrow fullscreen flow tour.
• pnpm lint, canvas and fork typechecks, fork tests, and the side panel browser tests.