Add simplex-ball connected components and starting points

[maria-zaza]

Adds utilities for identifying connected components of the simplex-sphere intersection and computing starting points for each component.

Main changes:

• Build graph over active simplex vertices outside the ball.
• Find connected components corresponding to simplex-ball spherical patches.
• Compute starting points by intersecting rays from an interior point with the sphere.
• Add approximate Chebyshev center helper for Δ ∩ B using lp_solve and cutting-plane linearization of the ball constraint.
• Add tests for segment-ball intersections, component detection, starting points, isolated active vertices, Chebyshev center, and the turnkey Chebyshev-based wrapper.

Tests:

• ./build/simplexintersectball_components_test
• ctest -R simplexball_components --output-on-failure