Engine: the setup checklist (Session::progress), returned by model.check

The analysis stages in order (geometry, seeds & partitions, mesh, material, section, sets,
boundary conditions, loads, step, solve, results), each done, next, todo, blocked or optional,
with the command that does it. Built on the command requirements; Solve also reads the model
check's first error.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UhhZMBTviDQxZvwnyP89fo

crates/engine/src/cmd/model.rs

@@ -57,11 +57,14 @@ fn units(s: &mut Session, p: &Value) -> Result<Value> {
 fn check(s: &mut Session, _: &Value) -> Result<Value> {
     let diagnostics = s.model.check();
     let errors = diagnostics.iter().filter(|d| d.severity == Severity::Error).count();
+    let first_error = diagnostics.iter().find(|d| d.severity == Severity::Error).map(ToString::to_string);
+    let progress = crate::progress::to_json(&s.progress_given(first_error));
     Ok(json!({
         "ready": errors == 0,
         "errors": errors,
         "warnings": diagnostics.len() - errors,
         "diagnostics": diagnostics,
+        "progress": progress,
     }))
 }