feat(tools): h5rs, pure-Rust HDF5 tools (ls, dump, stat, diff, check)

New workspace crate clawhdf5-tools with one binary, h5rs, built only on the
clawhdf5 facade and clawhdf5-format (no libhdf5, no C):

- ls [-r] [-v] FILE[/path]: h5ls's listing (same text in its first two
  columns) plus the datatype; -v adds address, link count, layout and chunk
  index, chunk size, storage, filters, datatype and attributes.
- dump [--json] [-A] [-p] [-d PATH] FILE: h5dump DDL (byte-identical to
  h5dump 1.14.6 on the test files) or hdf5-json.
- stat FILE: h5stat's object/link/rank/layout/filter/attribute counts, raw
  data and total size.
- diff [-r] [-q] [-d D] [-p R] A B [OBJ1 [OBJ2]]: structural and value
  differences, exit 0/1/2 like h5diff.
- check [--data] FILE: walks every object, parses every message, verifies
  the checksums of every v2+ structure (including the fractal heap blocks
  the library never checks), checks chunk indexes against their datasets
  and raw data for out-of-file or overlapping extents; every problem with
  its address.

Values over --max-bytes are reported, not read; dense-storage heaps are
verified before objects are read from them; panics are caught (exit 3).
Tests compare with h5ls, h5stat, h5dump and h5diff and with h5py's values,
and flip the checksum of every checksummed structure in a v1.14-format file.

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

crates/clawhdf5-tools/Cargo.toml

@@ -0,0 +1,23 @@
+[package]
+name = "clawhdf5-tools"
+version = "2.7.0"
+edition = "2024"
+rust-version.workspace = true
+license = "MIT"
+description = "h5rs: pure-Rust HDF5 command-line tools (ls, dump, stat, diff, check) without libhdf5"
+repository = "https://git.redclaw.dev/quantumclaw/clawhdf5"
+keywords = ["hdf5", "h5dump", "h5ls", "cli", "science"]
+categories = ["command-line-utilities", "science"]
+readme = "README.md"
+
+[[bin]]
+name = "h5rs"
+path = "src/main.rs"
+
+[dependencies]
+clawhdf5 = { path = "../clawhdf5", version = "2.7.0" }
+clawhdf5-format = { path = "../clawhdf5-format", version = "2.7.0" }
+serde_json = "1"
+
+[dev-dependencies]
+tempfile = { workspace = true }