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/engine/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
-name = "modelcraft-engine"
-description = "ModelCraft's command engine: every user-visible action as a command with a JSON form"
+name = "fieldcraft-engine"
+description = "FieldCraft's command engine: every user-visible action as a command with a JSON form"
 version.workspace = true
 edition.workspace = true
 license.workspace = true
@@ -9,17 +9,17 @@ license.workspace = true
 workspace = true
 
 [dependencies]
-modelcraft-model = { workspace = true }
-modelcraft-geometry = { workspace = true }
-modelcraft-mesh = { workspace = true }
-modelcraft-io = { workspace = true }
-modelcraft-decks = { workspace = true }
-modelcraft-solver = { workspace = true }
-modelcraft-explicit = { workspace = true }
-modelcraft-fem = { workspace = true }
-modelcraft-lbm = { workspace = true }
-modelcraft-parallel = { workspace = true }
-modelcraft-render = { workspace = true }
+fieldcraft-model = { workspace = true }
+fieldcraft-geometry = { workspace = true }
+fieldcraft-mesh = { workspace = true }
+fieldcraft-io = { workspace = true }
+fieldcraft-decks = { workspace = true }
+fieldcraft-solver = { workspace = true }
+fieldcraft-explicit = { workspace = true }
+fieldcraft-fem = { workspace = true }
+fieldcraft-lbm = { workspace = true }
+fieldcraft-parallel = { workspace = true }
+fieldcraft-render = { workspace = true }
 serde = { workspace = true }
 serde_json = { workspace = true }
 thiserror = { workspace = true }