- pointer events with pointer capture: a drag only starts on the canvas,
  continues outside it and ends on release; deltas from clientX/Y instead
  of the non-standard layerX (a drag entering from outside made the
  camera NaN)
- without WebGL 2 show a message in the page instead of an alert with raw
  HTML, and refuse to load files
- normal fallback for zero-area polygons used vec3.create(args), which
  ignores its arguments and returned a zero normal
- canvas resolution in device pixels (CSS size * devicePixelRatio), mouse
  movement stays in CSS pixels
- index.html: charset, viewport and lang

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Loading
- parse into fixed-size per-LOD blocks and upload them to the GPU while
  reading, so memory stays flat for multi-GB files (3.4 GB 3D-DLM loads
  with a JS heap below 90 MB) and the model is shown during loading
- load the single .gml (or .xml) inside a zip archive, decompressed as a
  stream, including ZIP64
- reject 7z/RAR/gzip and other non-XML input at once with a clear message,
  and enable the sax buffer limit that unterminated "<!" in binary data
  used to bypass until the tab ran out of memory
- decode UTF-8 across chunk borders, cancel a running load when a new
  file is chosen, report load errors

Geometry
- split coordinates on any whitespace (indented posList, one pos per line)
- subtract the origin in double precision before float32 conversion
- handle PolygonPatch, Rectangle and Triangle
- tag geometry with its LOD; setLodVisible() prepares LOD switches
- light brown for land use and relief, nested colours restore the parent

View
- bind shader attribute locations, check compile/link errors, free GPU
  buffers of the previous file
- infinite far plane with a near plane following the camera distance,
  starting distance fitted to the model without a 10 km cap
- minimum zoom step and distance, pan speed proportional to the distance

Tests: npm test (Node 22+), 73 tests

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>