Every control in the unified strip is now 28px tall: tb-btn (was 30),
Libraries (was 26), the C++/MicroPython select (was ~22), the board
selector, Serial/Scope, canvas icon buttons, zoom and Add (all were 32).
The explorer toggle moves inside the Code/Both/Circuit segmented group
as its first segment, and every active-segment blue is the Libraries
blue (var(--color-action-primary)) instead of the hardcoded #0e639c.
The editor zone's overlap floor becomes min-width: max-content — the
hardcoded 280px sat below the real content width, letting the console
button paint over the board selector when the docked chat narrowed the
bar. Now the zone can never shrink under its buttons; flex-wrap moves
the canvas controls to a second line instead. Also closes the gap
between the logo and the File menu (header gap 16->6, menubar
margin-left 14->2).
e9053f73fe