* fix(assimp): pass -f<format> so non-extension targets work
The assimp converter invokes `assimp export <in> <out>` and relies on
assimp's extension-based format inference to pick the output format.
That works for targets whose id happens to match a real file extension
(glb, gltf, obj, stl, ply, etc.) but silently fails for every target
whose assimp id is not a conventional filename extension:
glb2, gltf2, objnomtl, stlb, plyb, fbxa, assbin, assxml, pbrt, assjson
Picking any of those in the UI aborts the job with:
assimp export: no output format specified and I failed to guess it
assimp_cmd's `-f<h>` flag overrides extension inference, and the values
in `properties.to.object` already correspond 1:1 to assimp's format ids
(verified against `assimp listexport`). Passing `-f${convertTo}` makes
every advertised target work without changing anything else.
Reproduction: upload any .stl, convert to glb2. Before: ENOENT on the
nonexistent output file. After: valid binary glTF 2.0.
* fix(assimp): write real file extensions for non-extension format ids
Follow-up to the previous commit. With `-f<format>` now passed to
assimp, every advertised target exports successfully — but seven of
them still produce files with assimp's internal format id as the
extension, which no third-party viewer recognises:
glb2 → .glb2 (really binary glTF 2.0, should be .glb)
gltf2 → .gltf2 (text glTF 2.0, should be .gltf)
objnomtl → .objnomtl (OBJ without .mtl, should be .obj)
stlb → .stlb (binary STL, should be .stl)
plyb → .plyb (binary PLY, should be .ply)
fbxa → .fbxa (ASCII FBX, should be .fbx)
assjson → .assjson (JSON dump, should be .json)
Map these in `normalizeOutputFiletype`, the same helper that already
handles jpeg→jpg, latex→tex, markdown→md. The format id on `convertTo`
is untouched, so `assimp -f<id>` still selects the correct
encoding/variant — only the output filename changes.
assbin, assxml, and pbrt are both the format id and the canonical
extension, so they need no mapping.
* style(assimp): fix prettier formatting
