Tile directories start at level 1, so the map renders one level too large

• The map at zoom control 0 shows the level-1 picture while vectors sit at half the basemap scale
• Requests for `18/x/y.png` fall outside the 19-level directory and return blank images
• `tileload` logs `{ x: 0, y: 0, z: 1 }` although the client believes it is at zoom 0

1. List the tile root and check whether the smallest directory is `0` or `1`
2. Print `e.coords` in the `tileload` event and compare with the requested path
3. Compare the largest directory number with the configured `maxZoom`
4. Check `minNativeZoom` and `maxNativeZoom`, which change upscaling but not requested levels
5. Decide whether to shift the client or renumber the directory

Align the client with the directory by setting `minZoom: 1, maxZoom: 19`, or keep zoom 0 and add `zoomOffset: 1` so requests use `z + 1`; set `maxNativeZoom: 19` with a higher `maxZoom` to upscale instead of requesting missing levels.

map.on('tileload', e => console.log(e.coords, e.tile.src));
// tiles/1/0/0.png
// tiles/19/...

L.tileLayer('/tiles/{z}/{x}/{y}.png', {
  minZoom: 1,
  maxZoom: 19,
  tileSize: 256
}).addTo(map);
L.tileLayer('/tiles/{z}/{x}/{y}.png', {
  minZoom: 0,
  maxZoom: 18,
  zoomOffset: 1,        // 请求 z = zoom + 1
  tileSize: 256
}).addTo(map);

• Raising `maxZoom` to 19 while leaving `minZoom: 0`, which still requests a non-existent level 0
• Confusing `maxNativeZoom` with `maxZoom` and expecting it to shift the request level