docs: ZFP reads (changelog, README feature table, known issues)

ZFP (32013) was the one plugin filter still listed as UnsupportedFilter.
Conformance on tank, `conformance/run.sh --no-fetch` (2026-09-26): 600 of
697 files ok (baseline 599); h5ex_d_zfp.h5 is newly ok.

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

docs/known-issues.md

@@ -293,10 +293,14 @@ fill-value item that did is fixed).
   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.
+  **Fixed 2026-09-26** for ZFP (32013, `zfp` feature, also in
+  `plugin-filters`), read only: every H5Z-ZFP mode and type, bit-exact
+  against h5py + hdf5plugin 7.1 (`crates/clawhdf5/tests/zfp_interop.rs`);
+  h5ex_d_zfp now reads (conformance 600 of 697 ok, tank,
+  `conformance/run.sh --no-fetch`). **Still open:** clawhdf5 cannot write
+  Blosc2 or ZFP. Other filters (32023, Granular BitRound, too, since
+  2026-09-26 even with the `pcodec` feature) can be plugged in with
+  `filter_registry::register_filter`.
 - **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