Using std::span<const uint8_t> and std::memcpy to deserialize binary packet structs without violating C++ strict aliasing rules.

Direct pointer casting (reinterpret_cast<Header*>(buffer)) causes Undefined Behavior and compiler optimization miscompiles. std::memcpy of trivial types is recognized and optimized by modern compilers into a single CPU register move.

Adding bounds checking before slicing spans prevents buffer over-read security vulnerabilities.