Add ColorWheel component (hue/saturation wheel + lightness strip + hex input). themeStore gains accentIdx=-1 for custom mode and setCustom action. ThemeApplier uses getActiveAccent to support both presets and custom hex. Settings page shows "Свой" button; clicking reveals the color wheel inline. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>