design-system 3.2.0: control boundaries clear SC 1.4.11's 3:1 via --control-border

[malinfossum]

Closes #16.

.input/.textarea/.select and the bordered .btn variants drew their edge with --border, which measures 1.22–1.50:1 against the page in every theme and palette — under WCAG 2.2 SC 1.4.11 (AA)'s 3:1 for the visual information that identifies a control. No existing border token clears the bar, so this adds the dedicated control-boundary token the issue called for, per Malin's 2026-08-21 decision: fixed upstream, synced out, no consumer-local overrides.

What changed

• New token --control-border, set per theme and per palette, hue-matched to each ground, clearing 3:1 against both --page-bg and the --surface-2 field with headroom (every value ≥3.15:1). tidsro aliases its --border-strong, which was already tuned as its control affordance (4.17:1). Light mode carries one shared value since palettes keep the base light surfaces; wend needs its own dark value (the base one only reaches 2.7:1 on its lifted ground). classic and gold inherit :root's correctly and stay untouched.
• Controls point at it: .input/.textarea/.select and base .btn (so .btn-ghost too) directly; .btn-secondary/.btn-danger keep their hue by color-mixing 28% of their tint over the token, which keeps the floor. Hovers strengthen toward the text ink — --border-strong now sits below the resting boundary, so pointing hover at it would dim the edge.
• Decorative edges do not move: .card/.alert/.table/.toast/.modal keep --border, per the issue's scope, and a test pins that they never adopt the control token. --border/--border-strong values are unchanged.
• Tests (written first, watched fail): a new contrast loop asserts the 3:1 floor for the token and the composed secondary/danger borders across every theme × palette. The scope builder was extracted and now also covers tidsro and the _oled.css foundation, which the contrast loops had never checked. Floors, not equalities.
• DS 3.1.0 → 3.2.0, CHANGELOG entry, both web scaffolds re-extracted (bump-then-extract, per the Add the Kenaz and Tidsro brand palettes #13/design-system 2.1.0: stamp the Kenaz and Tidsro palettes, re-sync scaffolds #14 gotcha).

Verification

• node --test "tools/*.test.mjs": 68/68 pass locally (was 67; +1 new, and the extended kenaz/scope coverage rides existing tests). Link check green.
• Cascade verified in a real engine: computed border-color of a live .input and .btn-secondary checked across 11 palette × theme combos in the gallery via headless browser — every combo resolves the intended value, including wend's light mode falling back to the shared light token and tidsro's --border-strong alias.

Visual note: every input and bordered button gets a visibly stronger edge in every theme — that is the point of the fix, but it's a look change worth an eyeball in the gallery before merging.