v0.3.0

• Added: request-scoped values cross services in the W3C baggage header through a rasuvaeff/context WireCodec (#9). ContextMiddleware(wireCodec:) reads allow-listed values (invalid ones dropped, never thrown); PreflightClient/ContextClient (wireCodec:) append the context's values, keeping members already present and never overriding a key; percent-encoding and the 8192-byte / 180-member limits. Outgoing baggage is opt-in per client instance — never configure it on a client that calls a third party.
• Requires rasuvaeff/context ^0.3.
• CI: property regression corpus is cached between runs.