fix(bytecode): preserve iterator position after truncated push

[pengqima]

Summary

Make BytecodeIterator::skip_immediate consume at most the bytes that remain, keeping an exhausted iterator anchored to the original bytecode slice.

This is a follow-up to #3792.

Problem

After #3792 switched BytecodeIterator to the original unpadded legacy bytecode, a truncated PUSH can make get(immediate_size..) return None.

The previous unwrap_or_default() fallback then creates an empty slice unrelated to the original bytecode allocation. A later call to position() uses offset_from_unsigned relative to the original start pointer, which requires both pointers to belong to the same allocation.

Fix

Slice at min(immediate_size, remaining.len()) instead. This preserves the existing iteration behavior—all available immediate bytes are consumed and iteration ends—while retaining the original slice provenance.

A regression test covers calling position() after a partially truncated PUSH2.

Testing

• cargo fmt --all --check
• cargo test -p revm-bytecode --all-features
• cargo clippy -p revm-bytecode --all-targets --all-features -- -D warnings
• cargo check -p revm-bytecode --no-default-features