JP's clarification: a lane slot is for functionality that's
otherwise hard to reach, not a shortcut to a key already close at
hand. Enter and Esc sit right on the keyboard, so they never
occupy a slot; PgUp/PgDn have no physical key at all, so they take
over the prime F4/F5 pair from OK/Back. Top/End (Fn-layered) keep
F1/F2. F3 stays the lone slot a screen promotes its own fiddly
Ctrl-chord onto (chat's Paths/Retry, contactlist's Sort already
follow this and needed no change). Default Shift bank is now
empty across the board — pure overflow, per the original spec.
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>