Snapshot WIP: solver HP epic progress, BPHX/HX physics, BMAD skill refresh.

Capture uncommitted solver robustness work (regularization, domain errors, linear solver lifecycle, tube DP/MSH), web workbench updates, and synced BMAD skills across IDE agent folders before starting BPHX pressure-drop.

Co-authored-by: Cursor <cursoragent@cursor.com>

crates/solver/benches/residual_jacobian_assembly.rs

@@ -0,0 +1,40 @@
+//! Phase-0 benchmark: residual + Jacobian assembly pass over the full system.
+//!
+//! Measures the cost of evaluating all component residuals and analytical
+//! Jacobian entries once — the per-Newton-iteration work that dominates solver
+//! runtime for real cycles.
+
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+use entropyk_components::JacobianBuilder;
+use entropyk_components::ResidualVector;
+
+mod common;
+
+fn bench_residual_assembly(c: &mut Criterion) {
+    let (system, state) = common::build_mock_system();
+    let mut residuals = ResidualVector::with_capacity(system.full_state_vector_len());
+
+    c.bench_function("residual_assembly_mock", |b| {
+        b.iter(|| {
+            residuals.clear();
+            residuals.resize(system.full_state_vector_len(), 0.0);
+            let _: () = system.compute_residuals(&state, &mut residuals).unwrap();
+            black_box(());
+        });
+    });
+}
+
+fn bench_jacobian_assembly(c: &mut Criterion) {
+    let (system, state) = common::build_mock_system();
+
+    c.bench_function("jacobian_assembly_mock", |b| {
+        b.iter(|| {
+            let mut builder = JacobianBuilder::new();
+            let _: () = system.assemble_jacobian(&state, &mut builder).unwrap();
+            black_box(());
+        });
+    });
+}
+
+criterion_group!(benches, bench_residual_assembly, bench_jacobian_assembly);
+criterion_main!(benches);