feat(compress): route simple context frames through Rust

Dispatch ordinary dictionary-free ZSTD_compress2 calls through the Rust frame
compressor while retaining the original C implementation for advanced
contexts. Prepare the C workspace first so allocation downsizing and
static-context limits remain observable.

Mark successful Rust frames so a following one-shot
ZSTD_compressStream2(..., ZSTD_e_end) call uses the same output path. Other
streaming directives and advanced parameters remain on the C implementation.

Test Plan:
- RUSTC_WRAPPER= CARGO_BUILD_RUSTC_WRAPPER= cargo test --manifest-path
  rust/Cargo.toml --no-default-features --features compression
  zstd_compress::tests
- RUSTC_WRAPPER= CARGO_BUILD_RUSTC_WRAPPER= cargo clippy --manifest-path
  rust/Cargo.toml --no-default-features --features compression -- -D warnings
- cargo +nightly fmt --manifest-path rust/Cargo.toml -- --check
- make -B -C tests fuzzer
- ./tests/fuzzer -t114 -i1000 --no-big-tests -s1

The basic fuzzer run now reaches the existing Rust one-shot compression-ratio
limit at test 113; the new stateful reuse tests pass before that point.

lib/compress/zstd_compress_internal.h

@@ -516,6 +516,8 @@ struct ZSTD_CCtx_s {
     size_t outBuffFlushedSize;
     ZSTD_cStreamStage streamStage;
     U32    frameEnded;
+    /* The next one-shot stream call may reuse a Rust-compressed frame. */
+    unsigned rustSimpleCompress2Completed;
 
     /* Stable in/out buffer verification */
     ZSTD_inBuffer expectedInBuffer;