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/testkit/src/oracle.rs

@@ -5,7 +5,7 @@
 //! A case directory holds:
 //! - `expected.json`: the case's kind (theory, experiment, benchmark), source, status and its
 //!   quantities: how each is measured, the reference value, the tolerance and the reason for it;
-//! - `recipe.json`: the model as ModelCraft commands (a JSON array of `{"command", "params"}`,
+//! - `recipe.json`: the model as FieldCraft commands (a JSON array of `{"command", "params"}`,
 //!   each step optionally with an `id` that measures can read its output by); absent while a
 //!   case is pending;
 //! - `design.json` (optional): a SolidCraft script that builds the geometry, opened first;
@@ -21,7 +21,7 @@ use std::path::{Path, PathBuf};
 use std::sync::Arc;
 use std::time::Instant;
 
-use modelcraft_engine::Session;
+use fieldcraft_engine::Session;
 use serde_json::{Value, json};
 
 /// Fixture band: a result may move by this fraction of its size (and a thousandth of the
@@ -232,8 +232,8 @@ pub fn run_case(dir: &Path, expected: &Expected) -> Result<Vec<Result<f64, Strin
     let design = dir.join("design.json");
     if design.is_file() {
         let script = crate::corpus::read(&design).map_err(|e| e.to_string())?;
-        let bytes = modelcraft_geometry::script_design(&script).map_err(|e| format!("design.json: {e}"))?;
-        let opened = modelcraft_geometry::open_design(&bytes).map_err(|e| format!("design.json: {e}"))?;
+        let bytes = fieldcraft_geometry::script_design(&script).map_err(|e| format!("design.json: {e}"))?;
+        let opened = fieldcraft_geometry::open_design(&bytes).map_err(|e| format!("design.json: {e}"))?;
         if let Some(e) = opened.errors.first() {
             return Err(format!("design.json: feature {}: {}", e.feature, e.message));
         }
@@ -402,7 +402,7 @@ pub fn run(root: &Path, options: &Options) -> Result<(), String> {
                     }
                 }
                 let text = serde_json::to_string_pretty(&json!({
-                    "note": "ModelCraft's accepted results for this case, written by `cargo xtask oracle --bless`. A result outside its band fails CI.",
+                    "note": "FieldCraft's accepted results for this case, written by `cargo xtask oracle --bless`. A result outside its band fails CI.",
                     "values": values,
                 }))
                 .map_err(|e| e.to_string())?;
@@ -565,7 +565,7 @@ pub fn report(cases: &[(String, Expected)], rows: &[Row]) -> String {
         md,
         "# Verification and validation oracle\n\n\
 Generated by `cargo xtask oracle` from [`tests/oracle/`](../tests/oracle/); the policy is [verification.md](verification.md). \
-Every case is our own model, built with ModelCraft commands from the problem's published description, and compared with \
+Every case is our own model, built with FieldCraft commands from the problem's published description, and compared with \
 the reference value its `expected.json` cites, within the stated tolerance and for the stated reason. Accepted results are \
 frozen in each case's `fixture.json`: a later change that moves one beyond its band (10⁻⁹ of its size) fails CI even while \
 the reference still passes. No reference value was produced with a commercial product.\n\n\
@@ -589,7 +589,7 @@ benchmark, {} experiment; {} pending cases wait for capabilities still being bui
         };
         let _ = write!(
             md,
-            "## {heading}\n\n| Case | Quantity | Reference | ModelCraft | Error | Tolerance | Result | Fixture |\n|---|---|---|---|---|---|---|---|\n"
+            "## {heading}\n\n| Case | Quantity | Reference | FieldCraft | Error | Tolerance | Result | Fixture |\n|---|---|---|---|---|---|---|---|\n"
         );
         for (case, _) in &in_kind {
             for r in rows.iter().filter(|r| &r.case == case) {