[arzafran]

Summary

Settings now looks like a Mac System Settings window: icon tabs in the toolbar and grouped form sections, with a soft blur where content scrolls under the toolbar. In the main window, icons, text sizes and corner radii follow one scale, small buttons have a 24pt hit area, and on macOS 27 the titlebar controls sit where Finder puts them, on glass.

• Settings: toolbar icon tabs replace the segmented strip; System Settings grouped-section metrics; fixes to the font size field, sound preview button and theme picker; Finder-style scroll blur under the toolbar.
• Main window: shared icon, type and radius tokens; icon buttons at least 24x24; tab titles get an overflow menu; titlebar controls (bell, +, sidebar toggle) placed per macOS 27 and drawn full-strength on glass.
• Sidebar minimum width raised to 224 so titlebar controls clear the window buttons.

Linear: INC-584. Fixes INC-584

Testing

• check-structural-budgets.py, check-settings-docs.py, check-v2-contract.sh: pass locally.
• Two test files changed. BonsplitTabDragUITests is a contract change: a collapsed minimal sidebar now shows its controls after the traffic lights. WindowAndDragTests only gets a wider fixture.
• Built and checked by hand on a tagged Debug build on macOS 27.2.
• Not verified by hand: hover and pressed glass states, footer popover contents, overflow menu opening, the macOS 14/15 path.

Demo Video

Screenshots: before/after needed (author to attach).