Add SRS bounds check in KZG commit to prevent out-of-bounds slicing

[viktorking7]

Description

• Added a guard in KZG commit to cap polynomial coefficients by available SRS powers
• Prevents out-of-bounds slice and potential panic when SRS is underprovisioned
• Kept public API unchanged; behavior now safely truncates inputs instead of panicking

Why

• Ensure robustness against malformed or oversized inputs
• Avoid denial-of-service via runtime panics in critical crypto code paths