Add ByteBuffer struct (pointer + length + capacity)

[davidgaspardev]

Description

Implement a ByteBuffer struct that holds a data pointer alongside its length and allocated capacity, enabling safe handling of binary data (buffers that may contain \0 bytes in the middle).

typedef struct {
    bytes_t      data;
    unsigned int len;
    unsigned int cap;
} ByteBuffer;

Motivation

Current functions rely on null-terminated strings, which breaks for binary data. A ByteBuffer makes the length explicit and decouples it from the content.

References

• Dynamic array / buffer pattern — used in C++ std::vector, Rust Vec<u8>, Go []byte
• Wikipedia: Dynamic array
• Author of pattern: popularized by Brian Kernighan & Dennis Ritchie in The C Programming Language (1978) through manual buffer management idioms