0.3.8

• First release since 0.3.5. It also ships the 0.3.6 and 0.3.7 entries below, which were recorded
  but never tagged.
• Move to Harness 0.15.0 (Substrate 0.7.17). The model-backed TUI reaches its endpoint through
  Harness's llm adapter over llm 0.8.0; --api-key-env, --oauth-token-env and
  --oauth-token-file still resolve their credential for each request. Toolchain discovery comes
  from the tools repository's toolchain crate, through Harness's Substrate crate.