fix: download example circuit json asset

[vahapogut]

Fixes #11

Summary

• Link the example Circuit JSON file to the bundled Vite asset instead of the GitHub blob page.
• Add a download filename so browsers download usb-c-flashlight.json directly.
• Clean up the touched App file so Biome checks pass.

Verification

• bun x @biomejs/biome check src\App.tsx
• bun run build

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