fix(ui): minor polish — dark mode select, safe area bottom, error copy

[comnam90]

Summary

Three small UI polish fixes identified during a UX/accessibility review of layouts/index.html.

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1. Native <select> in Windows dark mode (line 611)

On Windows with system dark mode enabled, the native <select> element renders with the OS default dark background but inherits no explicit color/background-color from CSS, causing it to look broken. Add explicit overrides in the select CSS rule:

select {
    background-color: #1e293b; /* dark */
    color: white;
    /* existing rules... */
}
.light select {
    background-color: white;
    color: #0f172a;
}

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2. Missing bottom safe area on mobile (line 576)

The header correctly applies env(safe-area-inset-top), but the map container bottom has no env(safe-area-inset-bottom) padding. On iPhone with home indicator, the map's bottom edge is clipped behind the gesture bar.

Add to .map-container or the wrapping .app-container:

padding-bottom: env(safe-area-inset-bottom);

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3. Passive voice in error message (line 701)

"There was a problem loading the map."

Should be active:

"The map failed to load."

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Acceptance criteria

• Native <select> renders correctly in Windows dark mode (manual test)
• Map bottom edge is not clipped behind home indicator on iPhone (manual test or screenshot)
• Error message copy updated to active voice
• npm run test:ui passes