tests: jfjoch_portable_test, quick [portable] checks for the macOS and Windows jobs

A Catch2 executable that builds in the portable configurations (JFJOCH_VIEWER_ONLY /
JFJOCH_RUGNUX_ONLY) and links only what those build - JFJochRugnux, JFJochReader,
JFJochImageAnalysis, JFJochWriter, JFJochCommon - so it can run on the macOS arm64 and
Windows x64 jobs, where the receiver/broker/FPGA/HLS sources are not built and there is no GPU.
EXCLUDE_FROM_ALL, so a product build does not pay for it; catch2 is now made available in the
portable configure as well (it is EXCLUDE_FROM_ALL too).

The cases tagged [portable] cover what depends on the architecture, the compiler or the
standard library: bitshuffle/LZ4/zstd, HDF5 read-back (legacy/VDS/integrated, the direct-chunk
path), miniCBF/marCCD/SMV header parsing, CBOR, CPU spot finding, azimuthal mapping, Bragg
prediction/integration, gemmi MTZ/mmCIF. New in tests/PortableTest.cpp:
- a golden FNV-1a hash of two frames of compression_benchmark.h5, decoded from the raw chunk by
  the hperf and the classic bitshuffle and through the HDF5 filter (x86 hashes
  affea29c511b6ec2 / e46913009c95a1f1);
- a golden hash of a bitshuffle/LZ4 encode (the writer must produce the same bytes everywhere);
- the shipped bitshuffle block selector against the classic reference over elem 1/2/4/8 and
  block tails;
- the FFTW indexer, named explicitly, on a synthetic orthorhombic lattice (the existing FFT
  indexer lattice tests run only under CUDA);
- a 4-frame end-to-end rugnux run on the git-LFS rotation dataset (HDF5 via external links, CPU
  spot finding, indexing, integration); SKIPs when LFS was not pulled.
All 45 take ~4 s on Linux (~2 s without the LFS case), CPU-only build.

M_PI replaced by PI (common/JFJochMath.h) in the two tagged files that used it, as MSVC does not
define M_PI. The CBF gzip test shells out to gzip and is left untagged.

CI: build and run jfjoch_portable_test "[portable]" in build-windows (both variants),
build-rugnux-windows, build-macos-viewer and build-rugnux-macos, after the build and before
packaging.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01D1G8gJVAy6gp1K5Dz3NE5C

tests/LoadReferenceMtzFreeFlagsTest.cpp

@@ -42,7 +42,7 @@ namespace {
     bool ExpectedFree(int h, int k, int l) { return (h * 7 + k * 13 + l * 17) % 10 == 0; }
 }
 
-TEST_CASE("LoadReferenceMtz imports FreeR (CCP4 convention: test set = 0)", "[reference_mtz]") {
+TEST_CASE("LoadReferenceMtz imports FreeR (CCP4 convention: test set = 0)", "[reference_mtz][portable]") {
     const auto path = (std::filesystem::temp_directory_path() / "rugnux_freer_ccp4.mtz").string();
     WriteMtzWithFreeR(path, /*free_value=*/0);
     const auto ref = LoadReferenceMtz(path);