Move the floating mouse-mode palette into a rounded, translucent card
docked to the field's right edge, matching the v1 prototype: grouped
tools with thin dividers (navigate / cut / trace / annotate), an
active-tool accent state (accent fill + white icon + soft glow),
bottom-right keycap hints, and name + shortcut tooltips.

The card flips to the left edge when the left_handed option is set,
wired to the View-menu toggle; this also implements the toggleHandedness()
hook that checker.py already referenced. mode_x still records the docked
side so the field's corner-text painter keeps clear of the palette.

All tools, mouse-mode indices, keyboard shortcuts, and right-click dialogs
are preserved; the trace palette, increments, brightness/contrast, and
scale bar are untouched. theme.py gains per-scheme chrome tokens for the
card. Adds 16 headless tests covering structure, keycaps, the active
state, docking, and the left-handed flip.

…t/ui-palette-right

# Conflicts:
#	PyReconstruct/modules/gui/palette/mouse_palette.py