🐛 fix(docker): whitelist README.md in .dockerignore for hatchling builds

Both meeseeks_core and meeseeks_tools reference ../../README.md in
their pyproject.toml. The *.md exclusion removed it from the Docker
context, breaking uv pip install during image builds.

Author: bearlike

.dockerignore

@@ -30,6 +30,7 @@ docker.env
 # ── Documentation & meta ─────────────────────────────────────
 docs/
 *.md
+!README.md
 LICENSE
 
 # ── Test / CI artifacts ───────────────────────────────────────