build: reach the CAD stack through acadifc

The DWG/DXF/ACIS codec now lives in its own crate and acadifc re-exports
it alongside the geometry kernel, so this is the single dependency:

    OpenCADStudio -> acadifc -> { cadcodec, cadkernel }

acadifc is aliased to `acadrust`, which leaves the 2569 `use acadrust::…`
paths across 253 files untouched — the alias is a manifest-level rename,
not a source change.

The old `[patch.crates-io]` entry goes away with it: the dependency is a
git revision now rather than a crates.io version being redirected.

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

crates/ocs_web_worker/Cargo.toml

@@ -8,7 +8,7 @@ publish = false
 crate-type = ["cdylib"]
 
 [dependencies]
-acadrust = { version = "0.4", features = ["serde"] }
+acadrust = { package = "acadifc", git = "https://github.com/OpenAEC-Foundation/acadifc.git", rev = "08a3d71", features = ["serde"] }
 bincode = "1.3"
 console_error_panic_hook = "0.1"
 getrandom = { version = "0.3", features = ["wasm_js"] }