Design tokens: text in two tones, corners in four

[WaylandYang]

The four token changes the rest of the interface work sits on. Each is a separate commit.

• Secondary text clears the contrast line — --u-text-2 and --u-text-3 lift so the faint tier is legible.
• Four radius tiers, named by role — --radius-cell 4 / --radius-control 6 / --radius-panel 8 / --radius-overlay 12, and ui/ migrated to them. A corner now says what the thing is, which is what the guard can check; one absolute radius is not the same roundness on a 24px chip and a 300px panel.
• A panel is a slot for content (DESIGN.md rule 6) — a panel holds several things of the same kind; a list is one panel with rows, not one card per item. Hover belongs to the row, so .glass-hover is gone and the three surface fills narrow: a panel is a touch lighter than the ground, not a box drawn on it.
• The type scale moves up one step — 12/13/14/16/24 (was 11/12/13/15/20). Three tiers were crammed into 11–13px, where a 1px difference is invisible, and the "secondary" size had become the de facto body size.

pnpm guard and pnpm build clean.

🤖 Generated with Claude Code