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/WriteReflectionsTest.cpp

@@ -31,7 +31,7 @@ namespace {
     }
 }
 
-TEST_CASE("Merged MTZ: the data dataset is id 1 and carries the wavelength", "[write_reflections]") {
+TEST_CASE("Merged MTZ: the data dataset is id 1 and carries the wavelength", "[write_reflections][portable]") {
     jfjoch_test::SyntheticMergeParams params;
     params.true_space_group = "P 43 21 2";
     params.twin_supergroup = "P 43 21 2";
@@ -74,7 +74,7 @@ TEST_CASE("Merged MTZ: the data dataset is id 1 and carries the wavelength", "[w
 }
 
 TEST_CASE("Unmerged MTZ: LP is Lorentz-polarization, QE the sensor efficiency, FLIGHT the flight path",
-          "[write_reflections]") {
+          "[write_reflections][portable]") {
     // The whole point of the split: LP must mean what XDS and DIALS mean by it, and the raw count
     // sum must still be recoverable from the file alone, as I / LP * QE * FLIGHT.
     auto experiment = TestExperiment();