Add a selectable light notch surface on Windows

[abrahaofv]

Summary

• adds a Dark/Light Surface control under Windows Appearance
• persists the backwards-compatible light_surface setting and refreshes the notch immediately
• uses semantic neutral tokens so the light surface has off-white and white layers, soft black marks, grey borders and tracks, and restrained high-contrast usage colors

Scope

Windows only; the existing dark surface and its vivid usage palette remain the default.

Verification

ode scripts/check-ui-scripts.mjsn- ode --test test-codex-headline.cjsn-
ode --test scripts/test-ko-i18n.cjsn- ode --test test-light-surface.cjsn- cargo test --locked (132 passed, 3 ignored)

• measured light-surface contrast: primary text 14.19:1; muted text and usage states 5.18:1–5.81:1

[vinzdg]

Thanks @abrahaofv — and I'm sorry, because this is the second time this week you've hit a collision you had no way to see. I'm taking #320, which landed on the same idea a few hours earlier.

The deciding difference is scope: #320 themes the Settings window and the drag overlay as well as the notch, and it sets the appearance before the window is built (initialization_script), so there's no dark frame on the first paint. Yours applies the class after page load (ui/notch.html:1515), so a light notch flashes black on every launch, and Settings and the dropzones stay dark underneath it — a visibly half-done feature through no fault of the code.

Two things in yours are better than what landed, and I'd like them:

• Your windows/test-light-surface.cjs is a real guard. It isn't wired into .github/workflows/windows.yml, so it never ran — add it beside check-ui-scripts.mjs, test-claude-auth-ui.cjs, test-ko-i18n.cjs and test-codex-headline.cjs and it becomes one.
• Your config test covers more than Windows: a light appearance for the notch, and a Theme row in Settings #320's.

One thing to know for next time: bool_or_false (config.rs:184) calls bool::deserialize(deserializer).unwrap_or(false), which swallows the error but leaves the serde stream mid-token for any non-scalar value. Your test only covers a string, which is why it passes. Option<bool> plus unwrap_or is the safe spelling.

For the record, both of you independently solved the same real trap — the JS-drawn SVG arcs and card dots don't follow a CSS theme. Your neutral()/usageColor() helpers and #320's readPalette() are two good answers to it.

#318 and #319 are merged, by the way — thank you for those.