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/novelty-statement.md

@@ -91,7 +91,7 @@ is an open research question that this library is designed to investigate.
 
 ### 3.4 — Full test coverage of analytic invariants
 
-173 CGAL tests verify mathematically provable properties:
+176 CGAL tests verify mathematically provable properties:
 - Gauss–Bonnet: Σ(2π−Θᵥ) = 2π·χ(M) to machine precision
 - τ ∈ fundamental domain: three inequalities
 - Holonomy closure: [T_a, T_b] = Id (abelian for genus 1)
@@ -120,7 +120,7 @@ conformallab++ is a port of Stefan Sechelmann's Java ConformalLab (TU Berlin,
 ~850 commits, v1.0.0 2018, LGPL).  The port:
 
 - Replaces the custom Java halfedge structure (`CoHDS`) with `CGAL::Surface_mesh`
-- Replaces JUnit tests with GTest + CGAL test format (173 tests)
+- Replaces JUnit tests with GTest + CGAL test format (176 tests)
 - Adds Doxygen API documentation, CMake build, and CLI
 - Is MIT licensed (the Java original is LGPL)
 - Targets submission to the CGAL library as package `Discrete_conformal_map`