refactor: externalize shared primitives, remove shadcn mixing in tools

Shared components (components/ui/):
- slider-row.tsx: SliderRow — label + display value + Slider, replaces
  inline slider blocks in FileConverter, QROptions
- color-input.tsx: ColorInput — color swatch + hex text input pair,
  replaces repeated inline patterns in QROptions, KeyframeProperties,
  FaviconGenerator

Media tool (FileConverter.tsx):
- Remove all shadcn Select/SelectTrigger/SelectContent/SelectItem
- Replace with native <select> + selectCls (matches AnimationSettings
  and all other tools)
- Use SliderRow for video/audio bitrate and image quality sliders
- Net: -6 shadcn Select trees, consistent with every other tool

QROptions.tsx:
- Use SliderRow for margin slider (remove raw Slider import)
- Use ColorInput for foreground + background color pairs

KeyframeProperties.tsx:
- Use ColorInput for background color pair (keep local SliderRow which
  has a different layout with number input)

FaviconGenerator.tsx:
- Use ColorInput for background + theme color pairs

AnimationSettings.tsx:
- Remove dead bg-[#1a1a2e] per-option className (global CSS handles
  select option styling via bg-popover)

Delete:
- components/media/ConversionOptions.tsx — dead code (no imports),
  contained the shadcn Label/Input/Select/Slider patterns being replaced

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

components/animate/AnimationSettings.tsx

@@ -127,7 +127,7 @@ export function AnimationSettings({ config, onChange }: Props) {
           className="w-full bg-transparent border border-border/40 rounded-lg px-3 py-2 text-xs font-mono outline-none focus:border-primary/50 transition-colors text-foreground/80 cursor-pointer"
         >
           {EASINGS.map((e) => (
-            <option key={e.value} value={e.value} className="bg-[#1a1a2e]">
+            <option key={e.value} value={e.value}>
               {e.label}
             </option>
           ))}