v2.0.9

Local-MIP 2.0.9

• Added runtime certification for models whose activity arithmetic is provably exact in double.
• Uses double for certified models while retaining the existing long double fallback.
• Templated activity accumulation and incremental update kernels.
• Improved extended-precision constraint classification and final solution verification.
• Increased solution output precision to ensure lossless double round trips.
• Added comprehensive numerical boundary and regression tests.