Merge branch 'feat/p2b-blosc2' into feat/p2b-scale

# Conflicts:
#	CHANGELOG.md

docs/known-issues.md

@@ -221,11 +221,16 @@ fill-value item that did is fixed).
   bitshuffle, bzip2 and Blosc 1 (`bitshuffle`, `bzip2`, `blosc`, or
   `plugin-filters` for all), read and write, pure Rust; h5ex_d_lzf,
   h5ex_d_bshuf, h5ex_d_bzip2 and h5ex_d_blosc now read (conformance 573 of
-  697 ok). **Still open:** Blosc2 (32026 — hdf5plugin stores each chunk as a
-  Blosc2 super-chunk frame, and n-D chunks as B2ND arrays) and ZFP (32013);
-  both fail with an `UnsupportedFilter` error that names the filter, and
-  either can be plugged in with `filter_registry::register_filter` (32023,
-  Granular BitRound, too, since 2026-09-26 even with the `pcodec` feature).
+  697 ok). **Fixed 2026-09-26** for Blosc2 (32026, `blosc2` feature, also
+  in `plugin-filters`), read only: hdf5plugin's frames and B2ND arrays, every
+  codec and filter it offers; h5ex_d_blosc2 now reads (conformance 576 of
+  697 ok, tank, `conformance/run.sh --no-fetch`). Blosc2 frames using
+  dictionaries, lazy chunks, variable-length blocks, user-defined codecs or
+  registered filters (e.g. bytedelta) are refused with an error.
+  **Still open:** ZFP (32013) fails with an `UnsupportedFilter` error that
+  names the filter, and can be plugged in with
+  `filter_registry::register_filter` (32023, Granular BitRound, too, since
+  2026-09-26 even with the `pcodec` feature). clawhdf5 cannot write Blosc2.
 - **Wrong data: a chunk whose filters decode to fewer bytes than the chunk
   read with zeros for the missing bytes** (any filter; found reviewing the plugin
   filters). **Fixed 2026-09-26:** it is an error naming the chunk. A corrupt