Extends the native Rust marshalling to sequences and optionals (the Rust
counterpart of the cpp_native increment): a field maps to Vec<T> / Option<T>,
the repr(C) mirror gains the matching `{ ptr, len }` / `{ present, value }`
fields, and `to_c` now returns a holder owning the CStrings + C-array backing
(Vec/CString live on the heap, so the C struct's raw pointers survive the move
and the call). `from_c` reads seq/Option back out via slice + present-flag.
Unblocks the timer's complex (seq-of-structs / seq-of-strings / two optionals)
and schedule (three struct params). Verified end-to-end — the demo round-trips
typed ComplexResponse / ScheduleResult.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Splits the Rust codegen the way C++ is split: rename `rust.nim` -> `rust_cbor.nim`
(CBOR) and add `rust_native.nim` (native). Dispatch on `targetLang=rust` now
honours `-d:ffiMode` (native/cbor); the crates share file names so each mode
writes its own dir (rust_bindings vs rust_native_bindings).
`rust_native.nim` emits a `<lib>_native` crate — the Rust analogue of
`cpp_native`: `#[repr(C)]` POD mirrors + `extern "C"` native entry points
(ffi.rs); idiomatic structs with `to_c`/`from_c`, a holder owning the CStrings
for the call (types.rs); and a `<Lib>Node` whose methods marshal typed args in /
read typed struct returns out, blocking via std mpsc (api.rs).
First cut: scalar/string/bool/float/nested-struct fields (create/version/echo);
seq/Option params are SKIPPED, native events next. Verified end-to-end — the
generated crate builds and the demo round-trips a typed EchoResponse. Tasks:
genbindings_rust (CBOR), genbindings_rust_native.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
