CONTRIBUTING: what FieldCraft is, getting it running, where help is wanted most; README: downloads

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

README.md

@@ -22,6 +22,21 @@ solves, and shows the von Mises stress and the deformed shape (tip deflection 0.
 theory with shear 0.177 mm).
 [MP4](docs/media/ibeam-analysis.mp4) · regenerated by [tools/demo-video](tools/demo-video/README.md).
 
+## Download
+
+[![Download for macOS](https://img.shields.io/badge/macOS-Download-000000?style=for-the-badge&logo=apple&logoColor=white)](https://github.com/jyviko/fieldcraft/releases/latest)
+[![Download for Windows](https://img.shields.io/badge/Windows-Download-0078D6?style=for-the-badge)](https://github.com/jyviko/fieldcraft/releases/latest)
+[![Download for Linux](https://img.shields.io/badge/Linux-Download-FCC624?style=for-the-badge&logo=linux&logoColor=black)](https://github.com/jyviko/fieldcraft/releases/latest)
+
+- **macOS:** open the `.dmg` and drag FieldCraft into Applications (Apple silicon and Intel).
+- **Windows:** unzip and run `fieldcraft.exe`.
+- **Linux:** the `.AppImage` (allow it to run as a program), or the `.tar.gz`.
+- **Command line:** `fieldcraft-cli` ships in every package; AI agents connect to it over MCP
+  ([docs/mcp.md](docs/mcp.md)).
+
+Every release lists its checksums in `SHA256SUMS.txt`. Building from source is in
+[CONTRIBUTING.md](CONTRIBUTING.md#get-it-running-about-10-minutes-on-a-fast-machine).
+
 ## Hex meshing a part that does not sweep
 
 A filleted L-bracket with a hole through each leg cannot be swept in one piece. Split into 30