fix(desktop): polish onboarding (Welcome / PasteKey / ChooseModel)

[hqhq1025]

Summary

Token-discipline polish on the three onboarding screens (sweep 2 of the page-by-page polish — full audit at docs/research/27-pages-polish-audit.md).

After Settings #45 and chain-rewrite #46 converged on the same --text-* / --space-* / --tracking-* recipes, the onboarding flow was the only main surface still mixing raw text-[24px] / text-[14px] / text-[11px] / h-[40px] / h-[28px] values. This PR aligns it.

Component-level changes

File	What changed
onboarding/index.tsx (Stepper)	Drop raw text-[11px] tracking-[0.05em] for --text-2xs + --tracking-label; add <span class="sr-only">Step N of M</span> so screen readers get progress; gate the dot-grow animation behind motion-safe:.
onboarding/Welcome.tsx	Title goes text-[24px] → --text-xl with --tracking-heading/--leading-heading; subtitle and "where to get key" caption move to the same recipe as PasteKey/Settings; provider links use --text-xs/--duration-fast. PathButton: motion-safe:hover:-translate-y + active:translate-y-0 press-down.
onboarding/ChooseModel.tsx	Heading + description on shared recipe; ModelPicker chips bumped from h-[28px] to h-[var(--size-control-sm)] (32 px) to match the 40 px input rhythm and Settings; chips gain aria-pressed; cost/baseUrl notes align on --text-xs / --leading-ui.

Non-goals

• No new copy, no new i18n keys (zero zh-CN audit needed).
• No new tokens — every replacement uses tokens already in packages/ui/src/tokens.css.
• No layout overhaul; 480 px container card untouched. PasteKey was already token-clean and is not modified.

Coverage report (rest of the polish sweep)

The companion audit docs/research/27-pages-polish-audit.md (gitignored) maps each surface to its in-flight PR. Backlog filed for: preview states (loading/empty/error), Toast, CommandPalette, inline-comment anchoring, cross-platform chrome, sidebar resize. Those overlap with wt/ux-loading-stages, wt/preview-ux-v2, wt/feat-mobile-frame and need to land before another polish pass.

Test plan

• pnpm typecheck — clean.
• pnpm lint — 0 errors (1 pre-existing complexity warning in packages/core).
• pnpm --filter @open-codesign/desktop test — 138/138 pass.
• Manual: launch onboarding in pnpm dev, walk Welcome → PasteKey → ChooseModel in EN and zh-CN, light + dark.

PRINCIPLES

• ✅ Compatibility — render-only changes, no schema/IPC/contract touch.
• ✅ Upgradeability — token-driven; future theme work flips one variable.
• ✅ No bloat — net -8 LOC, no new deps.
• ✅ Elegance — removes the last raw-px outliers the audit flagged for this surface.

[github-actions]

Findings

• [Minor] Screen-reader step label is hardcoded in English, bypassing i18n — this introduces inconsistent accessibility language when users switch locale, evidence apps/desktop/src/renderer/src/onboarding/index.tsx:111
  Suggested fix:

  const t = useT();
  
  <span className="sr-only">
    {t('onboarding.stepper.progress', { current, total })}
  </span>

Summary

• Review mode: initial
• 1 issue found in added/modified lines.

Testing

• Not run (automation)

open-codesign Bot

[github-actions]

Hardcoded English text in an accessibility label bypasses the language toggle. Please localize this string through useT() so screen readers follow the selected locale.

const t = useT();

<span className="sr-only">
  {t('onboarding.stepper.progress', { current, total })}
</span>

[github-actions]

Findings

• [Minor] Screen-reader progress text is hardcoded in English, bypassing i18n and causing accessibility language mismatch when users switch locale, evidence apps/desktop/src/renderer/src/onboarding/index.tsx:111
  Suggested fix:

  import { useT } from '@open-codesign/i18n';
  
  function Stepper({ current, total }: { current: number; total: number }) {
    const t = useT();
  
    return (
      <div className="flex items-center gap-[var(--space-2)]">
        <span className="sr-only">
          {t('onboarding.stepper.progress', { current, total })}
        </span>
        {/* ... */}
      </div>
    );
  }

Summary

• Review mode: follow-up after new commits
• 1 issue found in added/modified lines.

Testing

• Not run (automation)

open-codesign Bot

[github-actions]

Hardcoded English text in an accessibility label bypasses the language toggle. Please localize this via so screen readers follow the selected locale.

[hqhq1025]

Superseded by #49 — overlapping onboarding scope. #49 is a strict superset (token cleanup + stepper role=progressbar a11y + Welcome motion-safe wrap + ChooseModel chip --size-control-sm). Closing to avoid conflicts.