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

crates/mesh/src/lib.rs

@@ -35,7 +35,7 @@ pub enum Error {
     #[error("invalid boundary surface: {0}")]
     Surface(surface::Defects),
     #[error(transparent)]
-    Model(#[from] modelcraft_model::Error),
+    Model(#[from] fieldcraft_model::Error),
 }
 
 pub type Result<T> = std::result::Result<T, Error>;