build: Add opencode tools for testing

.opencode/tools/ask262-evaluate-in-engine262.ts

@@ -0,0 +1,31 @@
+/**
+ * OpenCode custom tool: ask262_evaluate_in_engine262
+ * Executes JavaScript code in the engine262 engine and captures spec sections.
+ */
+
+import { tool } from "@opencode-ai/plugin";
+import { createEvaluateInEngine262Tool } from "../../src/agent-tools";
+
+export default tool({
+  description:
+    "Executes JavaScript code in the engine262 JavaScript engine and captures which ECMAScript specification sections are hit during execution. " +
+    "Returns JSON with importantSections and otherSections arrays. " +
+    "Use this to understand how specific JavaScript operations map to the ECMAScript spec. " +
+    "You can use ask262Debug.startImportant() and ask262Debug.stopImportant() in the code to mark important sections.",
+  args: {
+    code: tool.schema
+      .string()
+      .describe(
+        "JavaScript code to execute in engine262 (e.g., '[1,2,3].map(x => x * 2)')",
+      ),
+  },
+  async execute(args) {
+    const { code } = args;
+
+    // Create and execute tool (no external dependencies needed)
+    const evaluateTool = createEvaluateInEngine262Tool();
+    const result = await evaluateTool.func({ code });
+
+    return result;
+  },
+});