Repository hygiene pass (issue #39):
- Add `.editorconfig` mirroring ludic-fmt: 2-space indent, LF, UTF-8, trim
trailing whitespace and final newline by default; 4-space for Python
tooling; keep trailing whitespace in Markdown (hard line breaks).
- Reconcile `.gitignore`: root-anchor `/build/` and `/out.ppm`, normalise the
misleading `**.zip` glob to `*.zip`, and document that the Kenney art is
tracked *extracted* while the download/plugin zips are local-only. `.idea`
-> `.idea/`.
- Add a `bin/x clean` command that removes `build/`, the root `out.ppm`, and
stray `bin/*.tmp`, keeping the toolchain binaries so the running `x`
survives.
No generated artifacts land outside build/ or bin/, both of which are ignored.
Closes#39
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
