fix: normalize engineering checks across units

Convert pump-depth vs rod-length mismatch gating to meter-equivalent comparisons, add imperial coverage, and correct rod material mapping with exported helper tests while refreshing related GUI/docs copy.

Made-with: Cursor

solver-api/tests/solverClient.test.js

@@ -0,0 +1,26 @@
+import { describe, expect, it } from "vitest";
+import { rodTypeToProps } from "../src/solverClient.js";
+
+describe("solverClient rod type mapping", () => {
+  it("maps fiberglass rod type 3 to fiberglass properties", () => {
+    expect(rodTypeToProps(3)).toEqual({
+      E: 5.5e9,
+      rho: 1900
+    });
+  });
+
+  it("maps sinker and steel rod types to steel-like properties", () => {
+    expect(rodTypeToProps(2)).toEqual({
+      E: 2.05e11,
+      rho: 7850
+    });
+    expect(rodTypeToProps(0)).toEqual({
+      E: 2.05e11,
+      rho: 7850
+    });
+    expect(rodTypeToProps(1)).toEqual({
+      E: 2.05e11,
+      rho: 7850
+    });
+  });
+});