Function eval_script 

pub fn eval_script(
    script: &[u8],
    stack: &mut Vec<StackElement>,
    flags: u32,
    sigversion: SigVersion,
) -> Result<bool>

EvalScript: 𝒮𝒞 × 𝒮𝒯 × ℕ × SigVersion → {true, false}

Script execution follows a stack-based virtual machine:

1. Initialize stack S = ∅
2. For each opcode op in script:
   • If |S| > L_stack: return false (stack overflow)
   • If operation count > L_ops: return false (operation limit exceeded)
   • Execute op with current stack state
   • If execution fails: return false
3. Return |S| = 1 ∧ S[0] ≠ 0 (exactly one non-zero value on stack)

Performance: Pre-allocates stack with capacity hint to reduce allocations

In production mode, stacks should be obtained from pool using get_pooled_stack() for optimal performance. This function works with any Vec.