Add initial Pico-8 cartridges for testing

- Created test_cart.p8 with basic drawing functionality and a print statement.
- Created test_unix.p8 with a simple initialization function.

scripts/nodes/library/math/subtract.js

@@ -0,0 +1,41 @@
+import { createNodeModule } from "../../nodeTypes.js";
+
+/**
+ * Subtracts one numeric value from another.
+ */
+export const mathSubtractNode = createNodeModule(
+  {
+    id: "math_subtract",
+    title: "Subtract",
+    category: "Math",
+    description: "Subtract one number from another.",
+    searchTags: ["subtract", "math", "minus", "difference", "-"],
+    inputs: [
+      {
+        id: "a",
+        name: "A",
+        direction: "input",
+        kind: "number",
+        defaultValue: 0,
+      },
+      {
+        id: "b",
+        name: "B",
+        direction: "input",
+        kind: "number",
+        defaultValue: 0,
+      },
+    ],
+    outputs: [
+      { id: "res", name: "Result", direction: "output", kind: "number" },
+    ],
+    properties: [],
+  },
+  {
+    evaluateValue: ({ resolveValueInput }) => {
+      const a = resolveValueInput("a", "0");
+      const b = resolveValueInput("b", "0");
+      return `(${a}) - (${b})`;
+    },
+  }
+);