HDF5 2.0 native complex as a first-class type on read; Python libver=

- Datatype::parse returns Datatype::Complex for class 11 (also inside
  compounds, arrays and VL types) instead of the {r, i} compound view.
- Facade: DType::Complex(Box<DType>); read_complex_f32/f64 accept it.
- h5rs dump/ls/diff print native complex as h5dump/h5ls/h5diff 2.2.0 do
  (checked against a fixture written by h5py 3.16 / libhdf5 2.0.0);
  dump --json keeps the {r, i} compound (hdf5-json has no complex class).
- clawhdf5-wasm reads native complex datasets as [re, im] pairs.
- Python: clawhdf5.File(path, 'w', libver=...) with h5py's values,
  mapped to FileBuilder::libver_bounds; 'v108' output opens in HDF5 1.8.23.
- Docs: known-issues entry moved to Fixed (history), CHANGELOG, READMEs.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

examples/wasm-viewer/README.md

@@ -123,8 +123,12 @@ else throws an `Error` naming the type.
   `readHyperslab`). Files of 4 GiB or more are refused at open (wasm32).
   Every response body is cut off past the length asked for. More in
   `docs/known-issues.md`.
-- Compound, reference, opaque and variable-length-sequence datasets are
-  refused with an error. Attributes of those types are listed with
+- HDF5 2.0 native complex datasets read as `[re, im]` pairs: `dtype`
+  `complex<f64>`, `elementShape` ending in `2`, the parts interleaved in
+  the typed array.
+- Compound (h5py's complex numbers, a compound `{r, i}`, included),
+  reference, opaque and variable-length-sequence datasets are refused with
+  an error. Attributes of those types are listed with
   `value: null` and their `dtype`.
 - No Zstd or SZIP filters (they link C): such a dataset fails with
   `unsupported filter`. Deflate, shuffle, Fletcher-32, LZ4, N-Bit and