v1.0.0

The first stable release, completing the rewrite that shipped as 0.5.0.

Added

• no_std support behind the new std (default) and alloc features.
  default-features = false, features = ["alloc"] keeps the full API
  minus the std::io blanket implementations and the HashMap
  conversions; readers and writers are byte slices, Vec<u8>, or custom
  cbor2::io trait implementations. Without alloc the crate is a
  serialization/validation core: to_writer/to_slice/serialized_size,
  validate, the tag wrappers and the core header codec (the serde
  deserializer needs a heap; error messages composed at runtime are
  reduced to static ones).

• to_slice: encodes into a caller-provided buffer and returns the
  written prefix, without allocating. Available in every configuration.

• A RawValue type holding one item as validated, undecoded bytes (in
  the spirit of serde_json::value::RawValue): serialization splices
  the bytes into the stream untouched and deserialization captures them
  byte for byte — exact even for non-preferred spellings — for
  signature payloads, pass-through items and deferred decoding.
  TryFrom converts in both directions between RawValue and Value
  (decoding and encoding respectively).

• CBOR tags on containers: #[cbor(tag = 18)] wraps a struct in a tag
  (required on decode), alongside the integer map keys of 0.5.0.

• Value conversions to and from the common std types: From covers
  the primitive scalars, Option, byte arrays/vectors,
  String/&str/Cow<str>, HashMap/BTreeMap (any Into<Value>
  keys and values) and FromIterator into an array; TryFrom<Value>
  extracts every variant's payload, range-checked integers (the 128-bit
  forms accept bignums) and typed HashMap/BTreeMap with serde-style
  error messages.

• A cbor2::Cbor trait implemented by #[derive(Cbor)] (sharing its
  name with the derive macro, serde-style), exposing the declared
  protocol details at runtime: T::KEYS (the field name → integer key
  pairs) and T::TAG as allocation-free constants, plus a
  keys(&self) -> BTreeMap<String, i128> convenience method with
  alloc.

• The tools package, renamed from cbor_conv to cbor2-cli (published
  for the first time, also as 1.0.0), now ships a single cbor command
  line tool. Bare cbor shows each CBOR item as one line of diagnostic
  notation (RFC 8949 §8) with full wire fidelity — indefinite-length
  markers, undefined, bignums as plain integers; cbor decode
  pretty-prints items as JSON or, with --diag, as indented diagnostic
  notation; cbor encode converts JSON values to CBOR (replacing the
  old json2cbor/cbor2json binaries). The CBOR-reading commands take
  their input from stdin, a file, a hex string or a base64/base64url
  string, and everything is covered by end-to-end tests.

Changed

• The serde Serializer/Deserializer now run over the cbor2::io
  reader/writer traits. With the default std feature these are
  implemented for every std::io::Write/Read and cbor2::io::Error
  is std::io::Error, so existing code is unaffected.
• The derive feature's #[cbor2::int_keys] attribute macro is
  replaced by #[derive(cbor2::Cbor)], which generates the serde
  Serialize/Deserialize impls itself (serde's derives must not be
  repeated alongside it). Field names and the type name stay untouched —
  the protocol details ride on a hidden serde-remote shadow type — so
  the same types serialize to plain JSON with the original field names
  and no tag: serde_json::to_string(&v) just works.
• Error types implement the error trait through serde::ser::StdError,
  which is std::error::Error whenever std is available.