Update all doc test counts to 176 CGAL tests, 0 skipped

Propagates the new baseline (176 passed, 0 skipped) established by the
GradientCheck_Hessian implementation across all documentation files that
previously referenced the stale counts (174/173/170 + 1-2 skips).

Files updated: CLAUDE.md, doc/api/tests.md, doc/contributing.md,
doc/getting-started.md, doc/math/novelty-statement.md,
doc/math/validation.md, doc/math/validation-protocol.md, scripts/try_it.sh

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

doc/math/validation.md

@@ -14,7 +14,7 @@ cmake --build build --target conformallab_cgal_tests
 ctest --test-dir build -R cgal --output-on-failure
 ```
 
-All 173 tests pass (1 skipped by design — see `doc/api/tests.md`).
+All 176 tests pass, 0 skipped (see `doc/api/tests.md`).
 
 ---
 
@@ -260,7 +260,7 @@ im Phasen-Roadmap).
 
 Run these in order to validate the implementation:
 
-- [ ] `ctest --test-dir build -R cgal --output-on-failure` → 173 tests pass, 1 skip
+- [ ] `ctest --test-dir build -R cgal --output-on-failure` → 176 tests pass, 0 skipped
 - [ ] `cgal.GaussBonnet.*` all pass → topology is correctly read from mesh
 - [ ] `cgal.EuclideanFunctional.GradientCheck_*` pass → energy = integral of gradient
 - [ ] `cgal.PeriodMatrix.TauInFundamentalDomain_*` pass → SL(2,ℤ) reduction correct