Add schema regression tests for shorthand symbol model

tests/schema-regression.test.js

@@ -0,0 +1,34 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import schema from "../frontend/schemeta.schema.json" with { type: "json" };
+
+test("schema keeps streamlined symbol shorthand support", () => {
+  const symbol = schema?.$defs?.symbol;
+  assert.ok(symbol);
+  assert.deepEqual(symbol.required, []);
+  assert.equal(symbol.properties.template_name.type, "string");
+  assert.ok(Array.isArray(symbol.examples));
+  assert.ok(symbol.examples.some((v) => v.template_name === "resistor"));
+  assert.ok(symbol.examples.some((v) => v.category === "generic"));
+});
+
+test("schema supports built-in instance.part shortcuts without explicit symbols", () => {
+  const instance = schema?.$defs?.instance;
+  assert.ok(instance);
+  assert.ok(Array.isArray(instance.anyOf));
+  assert.ok(instance.anyOf.some((rule) => Array.isArray(rule.required) && rule.required.includes("symbol")));
+  assert.ok(instance.anyOf.some((rule) => Array.isArray(rule.required) && rule.required.includes("part")));
+
+  const partEnum = instance.properties?.part?.enum ?? [];
+  assert.ok(partEnum.includes("resistor"));
+  assert.ok(partEnum.includes("capacitor"));
+  assert.ok(partEnum.includes("generic"));
+});
+
+test("schema preserves per-pin UI edit metadata contract", () => {
+  const pinUi = schema?.$defs?.instance?.properties?.properties?.properties?.pin_ui;
+  assert.ok(pinUi);
+  const pinUiEntry = pinUi.additionalProperties;
+  assert.ok(pinUiEntry);
+  assert.equal(pinUiEntry.properties.show_net_label.type, "boolean");
+});