- _surfaces(): add VignetteOverlay.tscn alongside ParchmentPanel/DarkBay,
backed by a Palette.STEEL ColorRect so the dim is visibly rendering.
- _variations(): add ItemTileEmpty (next to filled ItemTile), ParchmentInset,
and DarkPanel stylebox nodes.
- _fonts(): new section rendering default serif body, Accent
(Architects Daughter), and Mono (JetBrains Mono) labels at real sizes.
- _swatches(): wrap each ColorRect in a VBoxContainer with a Mono caption
Label naming its Palette const, per spec's "labelled swatches."
No raw hex / Color(...) literals introduced; all colour via Palette.*, all
styleboxes via ThemeKeys.* variation names.
