v0.2.0

• Deadline propagation (#1): ContextMiddleware accepts an optional
  deadlineHeader; an incoming budget in whole milliseconds (1–999999999)
  shortens the configured timeout, a longer or malformed value is ignored.
  PreflightClient and ContextClient take deadlineHeader and send the
  remaining budget downstream.
• BC — correlation ids (#2): CorrelationId now validates its value
  (1–128 characters of A-Z a-z 0-9 . _ : -), adds isValid() and
  generate(). ContextMiddleware generates an id when the header is
  missing or invalid (injectable correlationIdGenerator), so every request
  has one, and stores it in the context. Both clients take
  correlationHeader to forward it; an explicit header on the request wins.
• Exception mapping (#3): with an optional responseFactory,
  ContextMiddleware turns ContextExpiredException into expiredStatus
  (504) and ContextCancelledException into cancelledStatus (499); off by
  default. Adds psr/http-factory to the requirements.
• BC — ContextClient (#4): rejects an object without a Guzzle-compatible
  request() method at construction; sends the body as its stream and keeps
  the protocol version; sets http_errors => false, so 4xx/5xx responses are
  returned like PSR-18; a transport failure after the budget ran out becomes
  ContextExpiredException with the transport exception as previous.
• Requires rasuvaeff/context ^0.2. Package brought up to the monorepo
  template (@api, #[Covers], missing repository files, README.ru.md,
  release workflow, runnable example).