ci: lint all targets, run interop suites for real, compile benches

- clippy --all-targets plus a clawhdf5-format feature matrix (parallel, lz4,
  zstd, pcodec, fast-checksum); fix the accumulated lint backlog in test,
  bench and feature-gated code (no behaviour changes).
- Install python3 + h5py/numpy/netCDF4/xarray in the CI container and set
  CLAWHDF5_REQUIRE_INTEROP=1, which makes a missing interop dependency a test
  failure. Every h5py/netCDF4 interop test used to skip silently in CI. Run
  the #[ignore]d writer_h5py_tests suite explicitly.
- cargo bench --no-run so benches can't rot; fix bench.rs and memory_bench.rs,
  which no longer compiled against the current strategy/consolidation APIs.
- Optional fuzz smoke run via CLAWHDF5_FUZZ_SECONDS.
- CHANGELOG and docs/known-issues.md updated.

Co-Authored-By: Claude Fable 5.1 <[email protected]>

crates/clawhdf5-format/src/attribute.rs

@@ -472,14 +472,13 @@ mod tests {
 
         // Name padded to 8 bytes
         data.extend_from_slice(name);
-        while data.len() % 8 != 0 || data.len() == 8 {
+        if data.len() % 8 != 0 || data.len() == 8 {
             // Pad name to 8-byte boundary from start of name
             let name_start = 8;
             let name_padded = pad8(name_size);
             while data.len() < name_start + name_padded {
                 data.push(0);
             }
-            break;
         }
 
         // Datatype padded to 8 bytes
@@ -749,11 +748,11 @@ mod tests {
         data.extend_from_slice(name);
         data.extend_from_slice(&dt_bytes);
         data.extend_from_slice(&ds_bytes);
-        data.extend_from_slice(&3.14f64.to_le_bytes());
+        data.extend_from_slice(&3.25f64.to_le_bytes());
 
         let attr = AttributeMessage::parse(&data, 8).unwrap();
         let vals = attr.read_as_f64().unwrap();
-        assert_eq!(vals, vec![3.14]);
+        assert_eq!(vals, vec![3.25]);
     }
 
     #[test]