Expose rounding routines: fix max_ellipsoid validation and documentation

[shauryasingh310-ops]

Expose rounding routines: fix max_ellipsoid validation and documentation

Resolves #30 - Expose new rounding routines

Changes:

1. Fix missing throw statement (src/rounding.cpp)

   • Add throw keyword to max_ellipsoid validation error
   • Ensures proper error handling when max_ellipsoid is used on V-polytopes/Zonotopes

2. Clarify rounding method restrictions (R/round_polytope.R)

   • Document that max_ellipsoid only works with H-polytopes
   • Fix typos: "mimimmum" → "minimum", "mee" → "isotropy"
   • Update default method documentation

Methods supported:

• min_ellipsoid: Works on all polytope types (H, V, Zonotope)
• max_ellipsoid: H-polytopes only (inscribed ellipsoid)
• isotropy: Works on all polytope types (SVD-based)

Result: All rounding routines now properly exposed and documented