fix(build): restore the no-default-features build, and drop lzma-sys

Two things the truck removal broke without saying so, both found by auditing
what is left in the manifest rather than by anything failing.

The cfg gate on `acis_export` ended up on `acad_to_render` instead, when that
module was put back after being deleted by mistake. `acad_to_render` is what
every entity converts through, so gating it left the wasm build — which is
what `--no-default-features` stands in for — unable to resolve it from thirty
places. It built at the commit before the migration and builds again now.

And deleting TRUCK_CHORD_FRAC took the constant but left its doc comment and
its `#[cfg]` behind, so the attribute landed on the next constant down and
gated a boundary-sampling tolerance that has nothing to do with solids.

lzma-sys was the last dependency in the manifest with nothing using it: no
code references it and nothing else in the tree pulls it in. The `solid3d`
feature it hung off still gates four places, so the feature stays.

Everything else declared is used. `getrandom` and `iced_widget` look unused
by grep and are not — the first is declared to turn on the feature the wasm
target needs from a crate half the tree pulls in, and the second is a
`[patch]` entry rather than a dependency at all.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Cargo.lock

@@ -29,7 +29,6 @@ dependencies = [
  "js-sys",
  "log",
  "lyon_tessellation",
- "lzma-sys",
  "naga 27.0.3",
  "ocs_plugin_api",
  "open",
@@ -3047,17 +3046,6 @@ dependencies = [
  "num-traits",
 ]
 
-[[package]]
-name = "lzma-sys"
-version = "0.1.20"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5fda04ab3764e6cde78b9974eec4f779acaba7c4e84b36eca3cf77c581b85d27"
-dependencies = [
- "cc",
- "libc",
- "pkg-config",
-]
-
 [[package]]
 name = "maybe-rayon"
 version = "0.1.1"