Remove sample identities from the repository; document the rule

Datasets may be confidential; sample names and measured unit cells committed to
the repo can leak outside the group working on them. Scrub existing occurrences
and add a "No sample identities in the repository" section to CLAUDE.md
(forbidden: sample/dataset names, internal codes, measured cells tied to a
sample; fine: space group / lattice / twinning descriptors).

- Comments: replace internal dataset codes and protein names with the
  crystallographic situation they illustrate (centred vs pseudo-symmetric,
  holohedral, cubic, F-cubic/hexagonal, ...).
- Docs: same, in the analysis/writer/stream references and example configs.
- Tests: rename sample-named identifiers, TEST_CASE names, file prefixes and
  asserted labels to neutral crystallographic names (e.g. tetragonal_uc);
  behaviour unchanged. Reduce the CrystFEL reference PDB to a bare CRYST1 cell
  file (cell.pdb) and rename the reference data file.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/RugnuxLargeTest.cpp

@@ -25,7 +25,7 @@ namespace {
     public:
         using Catch::EventListenerBase::EventListenerBase;
         void testRunStarting(Catch::TestRunInfo const &) override {
-            const bool rot = jfjoch_test::LargeDataFile("lyso_rotation_master.h5").has_value();
+            const bool rot = jfjoch_test::LargeDataFile("rotation_master.h5").has_value();
             std::cout << "[jfjoch_test] large dataset in " << jfjoch_test::LargeDataDir()
                       << ": rotation=" << (rot ? "yes" : "no")
                       << " ([large] tests skip when absent)" << std::endl;
@@ -40,10 +40,10 @@ namespace {
 
 CATCH_REGISTER_LISTENER(LargeDataListener)
 
-TEST_CASE("Rugnux_LysoRotation", "[large]") {
-    const auto master = jfjoch_test::LargeDataFile("lyso_rotation_master.h5");
+TEST_CASE("Rugnux_Rotation", "[large]") {
+    const auto master = jfjoch_test::LargeDataFile("rotation_master.h5");
     if (!master)
-        SKIP("lyso_rotation_master.h5 not available (git-lfs data not pulled)");
+        SKIP("rotation_master.h5 not available (git-lfs data not pulled)");
 
     RegisterHDF5Filter();
     JFJochHDF5Reader reader;