Convert every overlay (search, keymap, themes, devices, queue, track
info, lyrics, jump, load-URL, online search, provider search, provider
browser, file browser, playlist manager) from a centered modal into a
compact inline panel that replaces the playlist: a header line, a body
filling the same playlist region, and the help line. The now-playing,
visualizer, and controls chrome stays live above, matching the Ctrl+V
visualizer picker, and opening an overlay no longer shifts the layout
height.
A single activeOverlay() describes each overlay's header/help/body once
(method expressions, so no per-render Model copy), and all overlays share
the playlist row budget via effectivePlaylistVisible(). Removes the old
centered-modal renderers, per-overlay chrome builders, and the
measureChrome/measureOverlayVisible/centerOverlay scaffolding.
Add TestInlineOverlaysFitTerminal to guard against vertical overflow
across overlays and terminal sizes.
Bjarne Øverli