Rename the project to FieldCraft

Crates fieldcraft-*, binaries fieldcraft and fieldcraft-cli, the .fieldcraft file (format tag
fieldcraft/1, manifest fieldcraft.json), FIELDCRAFT_* environment variables, the MCP server
name, egui widget ids (fc_*), the app icon document FieldCraft.icon and its generated family,
docs and licences. No compatibility shim: no files of the earlier name exist.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

SECURITY.md

@@ -1,9 +1,9 @@
 # Security policy
 
-ModelCraft is young; only `main` and the latest release get fixes.
+FieldCraft is young; only `main` and the latest release get fixes.
 
 Please **don't open a public issue** for a security problem. Report it privately through the
-repository's [Security tab](https://github.com/jyviko/modelcraft/security/advisories/new) with
+repository's [Security tab](https://github.com/jyviko/fieldcraft/security/advisories/new) with
 what you found, how to reproduce it (a model, deck or script), the version and platform, and the
 impact you expect.