Renamed the vestigial Lemon/default font-switch naming (setLemonFont/
isLemonFont/drawLemonChar/lemonXAdvance/_use_lemon -> setSingleFont/
isSingleFont/drawGlyph/glyphXAdvance/_single_font) across DisplayDriver.h
and both concrete drivers -- both have been permanently single-font for
several commits, so the old names invited a future reader to think a
real switch still existed. Pure identifier rename, no logic changed.
Also extracted the byte-identical "SenderName: " prefix-splitting in
MyMeshBot.h's tryBotReplyChannel()/tryBotChannelCommand() into a shared
botChannelSenderSplit(), mirroring the existing botRoomSenderName().
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
273fbfde7a