JSON Chart Structure Example:
{
"id": "unique-id",
"title": "Song Name",
"artist": "Artist",
"mp3": "https://example.com/song.mp3" // or "data:audio/mpeg;base64,...",
"offset": 0,
"difficulty": "Normal",
"notes": [
{ "time": 1.54, "lane": 1 },
{ "time": 2.13, "lane": 2 },
{ "time": 2.47, "lane": 3 },
{ "time": 2.80, "lane": 4 }
]
}