Import library notices

These independent libraries power local file conversion. Original copyright and licence terms apply. Bundled runtimes are unmodified.

• occt-import-js 0.0.23 — LGPL 2.1 licence; source and build instructions.
• Open CASCADE Technology — LGPL 2.1 with additional exception; runtime build configuration. Shared WebAssembly runtime is loaded independently and can be replaced by a compatible build.
• rhino3dm 8.35.0 — MIT licence; source.
• fflate 0.8.3 — MIT licence.
• fast-xml-parser 5.11.2 — MIT licence.
• dxf-parser 1.1.2 — MIT licence.