Unify CBOR std::byte and uint8_t byte-string handling

[stephenberry]

Follow-up to #2650. That PR fixed std::byte and fixed std::array<char, N> handling across the binary codecs, but left CBOR's std::byte and uint8_t byte handling implemented two different ways:

• std::byte ranges were handled by a single concept-based specialization (any contiguous std::byte range → byte string).
• uint8_t ranges were handled only by enumerated specializations for std::vector<uint8_t> and std::array<uint8_t, N>.

So any other contiguous uint8_t range (e.g. std::span<uint8_t>) silently fell through to the generic array writer and was encoded as an RFC 8746 typed array instead of a byte string, while the equivalent std::span<std::byte> was a byte string. MsgPack already treats these uniformly via byte_like; CBOR was the outlier.

Change

Collapse the duplicated specializations into one read/write pair each, constrained on the existing glz::contiguous_byte_range concept (byte_like = std::byte, unsigned char, uint8_t), and widen the generic array specializations' exclusion to match:

• write.hpp: 4 byte-string writers (std::byte range + std::vector<uint8_t> + std::array<std::byte, N> + std::array<uint8_t, N>) → 1.
• read.hpp: 3 byte-string readers (std::byte range + std::vector<uint8_t> + std::array<uint8_t, N>) → 1. The existing std::byte reader already handled both resizable and fixed-size targets with the max_array_size safety checks, so the two uint8_t readers were redundant subsets of it.

Net −293 / +72 lines.

Behavior

Every contiguous byte-like range now encodes as a CBOR byte string (major type 2) and the variants are cross-readable on the wire, regardless of element type or container. std::vector<uint8_t> / std::array<uint8_t, N> round-trips and wire bytes are unchanged.

One intentional wire-format change: previously-uncovered uint8_t containers such as std::span<uint8_t> now encode as a byte string instead of an RFC 8746 typed array, making them consistent with std::span<std::byte>. (Numeric typed arrays for other element types, e.g. int32_t/float, are unaffected.)

Tests

All existing CBOR tests pass (239), plus 4 new regression tests: identical byte/uint8 encodings, std::span<uint8_t> as a byte string, and byte ↔ uint8 cross-readability for vectors and fixed arrays. Verified locally under clang -std=c++23, plain and ASan+UBSan (243 tests / 961 asserts, 0 failures).