ci: exercise the full public API in the release smoke test (#67)

* ci: exercise the full public API in the release smoke test

Since each smoke leg pays for a fresh runner/container spin-up, expand
what one run verifies instead of adding more legs. Smoke.java now
touches essentially every public entry point in the zstd module:

- version/sizing info, core + bounded decompress, zero-copy
  decompressedSize(MemorySegment)
- deterministic error paths (undersized buffer -> DST_SIZE_TOO_SMALL,
  corrupted checksum trailer -> CHECKSUM_WRONG)
- ZstdFrame introspection (byte[] and MemorySegment overloads) and
  skippable frames
- ZstdCompressContext/ZstdDecompressContext: parameters, all reset
  directives, sizeOf(), prefix (delta) compression
- all 6 dictionary training variants, digested compress/decompress
  dictionaries (every constructor), refDictionary
- zero-copy streaming (ZstdCompressStream/ZstdDecompressStream,
  progress()) and java.io streaming (ZstdOutputStream/ZstdInputStream,
  withPledgedSize)
- ZstdBounds for every compress/decompress parameter, ZstdErrorCode
  descriptions

Deliberately excludes multithreaded compression (NB_WORKERS > 0): the
bundled native library is single-threaded, so exercising it would only
prove the parameter is a no-op.

Compiled and run locally against a fresh build (zstd-0.7.jar +
zstd-native-osx-aarch64-0.7.jar) before pushing.

* ci: dedupe round-trip helpers and narrow smoke test scope

Two follow-ups from review on #67:

- Extract shared helpers for the compress/decompress round-trip
  patterns that were copy-pasted across zeroCopyContextCompression,
  streamingZeroCopy, and streamingIo (plain vs. dictionary variants),
  and collapse the repeated check(Arrays.equals(...), msg) pattern
  into a checkArrayEquals helper used throughout.

- Narrow scope: this file's job is proving the released native
  artifact loads and links on this specific OS/arch/libc, and that
  off-heap MemorySegment interop and native struct layouts (streaming
  buffers, frame progression) work there — not re-deriving full API
  correctness, which the module's JUnit suite already covers more
  thoroughly with precise single-platform failures. Dropped the
  parameterBounds()/errorCodeDescriptions() enum sweeps, the 6-way
  dictionary-training-variant sweep, dictionaryIdApi()'s pure-Java
  record assertions, and the redundant dictionary-attachment/overload
  permutations (per-call vs. sticky vs. MemorySegment vs. digested vs.
  refDictionary), keeping one representative path per category. Cuts
  the file from ~610 to ~390 lines.

Compiled and ran locally against zstd-0.7.jar + zstd-native-osx-aarch64-0.7.jar.

Author: dfa1