Port the TS applySemanticPalette 56-token palette (22 themed light/dark
colors on a Mode axis, 6 chart singles, 28 numerics) and wake the
dormant variables.rs seeding path. Merge semantics differ from TS:
editor-core set_variables_bulk extends (incoming wins) while TS keeps
existing values, so the snapshot computes the missing set first and
seeds only absent tokens via one MergeThemePreset; rollback removes
exactly the created names/axes when no content survives. Live-smoke
verified: generated .op carries the 56 vars + Mode axis and $color-*
refs resolve at paint.
a9b0e729fd