v1.13.0

Dependencies

• Tasks now builds with Go 1.27. encoding/json/v2 is the default JSON
  implementation in this release; Tasks' stored task data, config, and API
  payloads round-trip unchanged, and GOEXPERIMENT=nojsonv2 remains as an
  escape hatch. The testdata/external-tui-consumer module moves with it, so
  the embedded-host contract keeps compiling against the same directive as the
  library it consumes.
• This release exists so the td / Tasks / Sidecar trio share one toolchain:
  Sidecar resolves its CI Go version from its own go.mod, so it can only pin
  a Tasks that declares a directive its toolchain already satisfies.