refactor(frontend): Button without className; toggles, adornments and special shapes on react-aria

[Kadrian]

Design-system prep, step 8: Button without className

Stacked on #4007. Button no longer takes a className, so nothing can be styled past the design system; TypeScript keeps it that way. The 57 sites that passed one were sorted into three kinds.

• layout belongs to the parent: margins moved into gaps and wrappers, a grid wrapper stretches a button to full width (history navigation, login, modal footers, form header)
• it was a different look: "reset" and the download link in the queries list are link, which flows with the surrounding text; danger is its own axis, allowed on secondary and tertiary only (the types say so), so the delete confirmation is a secondary danger and the error retry and the excluded-timestamps indicator are tertiary dangers
• it was not a design-system button: the input adornments (clear, calendar, search, the select box's reset and toggle, the toast's close) and the special shapes (scroll-to-top, the info pane's collapse strips, the two-tone run button, the badge chip) are react-aria Buttons or ToggleButtons styled where they live
• toggles are toggles: ui-components/ToggleButton is react-aria's ToggleButton in Button's look, sharing its sizes and the secondary and tertiary intents; highlight says how it shows while selected, the primary color or red for a warning state (negate, exclude). Everything whose look reflects an on-or-off state uses it, also where pressing opens an editor: folders, pin, table selection, the datepicker's year and month, and the editors' edit, dates and date actions. aria-pressed on Button is gone. The segmented control is ToggleButtonGroup now. The history sidebar is a vertical react-aria Toolbar of tertiary toggles and buttons, arrow keys move along it; the badge chip is a toggle too
• buttons are font-medium; the download split button and the name input are 30 px; the picture icons (empty editor arrow, empty history, upload success) keep their size via size-*

Worth a look: the history sidebar, negate and exclude in the editors, the badge chips in the entity header, the run and download buttons.