LeanHttp 0.2.0

Added

• Composable request constructors for GET, POST, PUT, PATCH, DELETE, and HEAD,
  with JSON, authentication, header, path-segment, and query-parameter helpers.
• Body.ofJson and Request.json for values with Lean.ToJson instances.
• Compile-time checked uri!, headerName!, and headerValue! literals,
  enabled by opening LeanHttp or its scoped syntax.
• Session.requestAs and LeanHttp.requestAs for decoding fully configured
  requests, plus Response.decodeAs for existing responses.
• ToBody instances for Body and Unit, allowing explicit bodies and empty
  payloads in Session.exchange.
• LeanHttp.packageVersion, used in the default user agent.
• Regression coverage for checked literals, query encoding, method preservation,
  typed request settings, decoding failures, and session reuse.

Fixed

• Requests with a GET method and a body now reach the server as GET, preserving
  the payload. Previously, setting the body caused libcurl to send POST.
• Supplying a body to HEAD no longer changes the method to POST or enables
  response-body downloads. libcurl's HEAD behavior does not send that payload.
• The new query helper preserves literal + characters in names and values,
  working around the query-encoding behavior in Lean 4.33.0. Repeated parameters
  retain their order.

Changed

• Session.getAs and Session.exchange share the same status and decoding
  implementation as Session.requestAs, preserving their existing signatures.
• The default user agent is now leanhttp/0.2.0.
• Session.Config.userAgent and Opt.userAgent now require a validated
  Std.Http.Header.Value instead of String. Migrate custom agents to
  headerValue!"my-client/1.0"; validate dynamic values with
  Std.Http.Header.Value.ofString?. This excludes CR, LF, and NUL before the FFI.
• Installation examples pin the release tag instead of main.