tests: port HyperIdealVisualizationPlugin circle-projection tests

Implements getEuclideanCircleFromHyperbolic() in C++ (hyperboloid model
→ Poincaré disk via Lorentz boost + circumcircle). Ports the 2 Java tests
that were the only remaining candidates not requiring HDS or a solver.

All other unported tests (DataTypesTest, SchottkyIOTest,
UniformizationDataTest, BranchedCoverTorusTest) are blocked by XML
serialization or HDS – stubs remain for Phase 4.

Test totals: 36 registered | 23 passed | 13 skipped | 0 failed.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

code/tests/CMakeLists.txt

@@ -6,6 +6,7 @@ add_executable(conformallab_tests
     test_surface_curve_utility.cpp
     test_discrete_elliptic_utility.cpp
     test_p2_utility.cpp
+    test_hyper_ideal_visualization_utility.cpp
 
     # ── Stubs: blocked until HDS port (Phase 4) ──────────────────────────────
     # All tests call GTEST_SKIP() with a clear explanation.