optimize: Compute v_init opening without polynomial instantiation

[DeVikingMark]

Optimizes the computation of v_init polynomial opening in ReadWriteMemory verifier by directly computing the evaluation value without creating the full polynomial. This improves performance by:

• Eliminating the need to allocate a large vector for coefficients storage
• Reducing the number of operations when computing polynomial value
• More efficient memory usage

The optimization is achieved by computing the polynomial evaluation directly at the evaluation point, accumulating contributions from bytecode and input data while tracking powers of the evaluation point.

Resolves TODO(moodlezoup) comment in read_write_memory.rs