feat(settings): theme scheduler, UI scale, CustomSelect scroll fix

- Time-based theme scheduler: auto-switches between day/night theme
  based on configurable times; setInterval re-checks every minute
- UI scale slider (80–150%) via CSS zoom on document root; preset
  buttons aligned to actual slider positions
- CustomSelect: scroll listener keeps dropdown anchored on scroll
- All features i18n in 7 languages

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/CustomSelect.tsx

@@ -25,15 +25,14 @@ export default function CustomSelect({ value, options, onChange, className = '',
 
   const selected = options.find(o => o.value === value);
 
-  useLayoutEffect(() => {
-    if (!open || !triggerRef.current) return;
+  const updateDropStyle = () => {
+    if (!triggerRef.current) return;
     const rect = triggerRef.current.getBoundingClientRect();
     const MARGIN = 6;
     const maxH = 240;
     const spaceBelow = window.innerHeight - rect.bottom - MARGIN;
     const spaceAbove = rect.top - MARGIN;
     const useAbove = spaceBelow < 80 && spaceAbove > spaceBelow;
-
     setDropStyle({
       position: 'fixed',
       left: rect.left,
@@ -44,6 +43,17 @@ export default function CustomSelect({ value, options, onChange, className = '',
       maxHeight: Math.min(maxH, useAbove ? spaceAbove : spaceBelow),
       zIndex: 99998,
     });
+  };
+
+  useLayoutEffect(() => {
+    if (!open) return;
+    updateDropStyle();
+  }, [open]);
+
+  useEffect(() => {
+    if (!open) return;
+    window.addEventListener('scroll', updateDropStyle, true);
+    return () => window.removeEventListener('scroll', updateDropStyle, true);
   }, [open]);
 
   useEffect(() => {

src/components/ThemePicker.tsx

@@ -9,7 +9,7 @@ interface ThemeDef {
   accent: string;
 }
 
-const THEME_GROUPS: { group: string; themes: ThemeDef[] }[] = [
+export const THEME_GROUPS: { group: string; themes: ThemeDef[] }[] = [
   {
     group: 'Games',
     themes: [