Fix onMouseDown event propagation, unstable gradient IDs, and TypeScript errors

[Copilot]

Several bugs and type errors existed across Svg, App, and missing type declarations — including a runtime crash path and a React anti-pattern.

src/Svg/index.tsx

• Runtime bug: onMouseDown(event) was called as onMouseDown() — dropping the event. CircularSlider.onMouseDown calls event.preventDefault() / event.stopPropagation(), so this throws a TypeError at runtime when trackDraggable is enabled and a click is processed mid-drag.
• Anti-pattern: Math.random() was called on every render to produce the SVG gradient ID. Moved to useRef so the ID is stable across re-renders — avoids unnecessary reconciliation and flickering in StrictMode.

// Before — new ID on every render, onMouseDown called without event
const gradientId = `radial-${label}-${Math.random()...}`;
onMouseDown();

// After — stable ID, event correctly forwarded
const gradientIdRef = useRef(`radial-${label}-${Math.random()...}`);
onMouseDown(event);

src/App.tsx

• Typed sliderRefs as React.useRef<React.RefObject<CircularSliderHandle | null>[]> with createRef<CircularSliderHandle>() — fixes the four ref= TS2322 errors and enables ref.current.refresh() access.
• Added explicit (index: number) to handleTabChange — removes implicit any.
• Annotated styles as Record<string, React.CSSProperties> — resolves TS2322 on CSS properties (flexWrap, textAlign, overflowX) inferred as string.
• Replaced deprecated border="0" HTML attribute on <input> and <img> with style={{ border: 0 }}.

src/vite-env.d.ts (new)

Added type declaration for *.svg?react Vite/SVGR imports — resolves TS2307 module-not-found errors for DragIcon and EmojiIcon.

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