docs: clawhdf5-wasm in the changelog, known issues and CLAUDE.md

Changelog entry with the sizes measured on tank on 2026-09-26 (and the
h5wasm 0.10.3 comparison), the browser build's limits as a known-issues
entry, and where its tests run.

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

CLAUDE.md

@@ -150,6 +150,14 @@ Cargo workspace with 17 crates under `crates/` (plus `libaec-sys`, an internal F
   `MemorySource` for this bookkeeping is inferred from the caller-supplied
   `source_channel` string (a heuristic, not an authenticated trust boundary).
 - GPU-accelerated vector distance computation (`clawhdf5-gpu`, wgpu); HDF5 I/O itself is CPU-only
+- Browser: `clawhdf5-wasm` (wasm-bindgen, read-only, file held in memory;
+  no Zstd/SZIP since they link C) and the `examples/wasm-viewer/` page.
+  `examples/wasm-viewer/test/run.sh` builds the package (needs the
+  `wasm-bindgen` CLI at the crate's exact version) and tests it under Node
+  and headless Chromium (a Playwright download in `~/.cache/ms-playwright`
+  on tank); the CI container has neither, so CI runs the native
+  `clawhdf5-wasm` `h5py_interop` test on the same fixture. Size numbers are
+  in the example's README.
 - Python and Node.js bindings for cross-language use
 - NetCDF-4 compatibility for scientific data interop