v0.4.0

Binaries for Linux (x86_64) and Windows (x86_64). Each archive holds
eg, eg-mcp, the README and the licences.

The Linux binary needs glibc 2.39 or newer — Ubuntu 24.04, Debian
13, Fedora 39+, RHEL 10. That floor comes from the prebuilt ONNX
Runtime this links, not from ExcelGRAG: it requires glibc 2.38 and a
GCC 13 libstdc++, so an older build host produces no binary rather
than a more portable one.

eg carries no runtime dependencies: ONNX Runtime is linked in, and
the embedding model is downloaded on first use to
~/.cache/excelgrag/models (EG_MODEL_CACHE overrides the location,
and --lexical-only skips it entirely).

Verify a download against the .sha256 file beside it.

What's Changed

• An agent harness, a bundled model, and investigate turns in the GUI by @sjvrensburg in #13

Full Changelog: v0.3.5...v0.4.0