v0.1.5-rc.4

What's Changed

• docs: reframe around context engineering platform; drop plan.md/progress.md refs by @rstagi in #51
• v0.1.5: telemetry — core-owned trace stream, JSONL by default, ratel inspect by @rstagi in #52

Full Changelog: v0.1.5-rc.3...v0.1.5-rc.4