POC: vscode-free @cline/sdk driver with unit test (Feature #2)

fetchSdkSummary() dynamic-imports the ESM-only SDK and returns its build
version + builtin tool catalog (pure, key-free). Kept vscode-free so it is
unit-testable in Node; test asserts a semver version and the read_files tool.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/cline.ts

@@ -0,0 +1,34 @@
+/**
+ * vscode-free driver for @cline/sdk.
+ *
+ * @cline/sdk is ESM-only (Node >=22) and uses createRequire(import.meta.url),
+ * so it must NOT be bundled into the CJS extension. We load it at runtime via
+ * dynamic import(); the bundler keeps it external (see esbuild.mjs).
+ */
+
+export interface ClineTool {
+  id: string;
+  description: string;
+}
+
+export interface SdkSummary {
+  version: string;
+  tools: ClineTool[];
+}
+
+/**
+ * Drive @cline/sdk with pure, key-free calls and return a renderable summary:
+ * the SDK build version and the agent's builtin tool catalog. Proves the SDK
+ * is linked and callable from the extension host.
+ */
+export async function fetchSdkSummary(): Promise<SdkSummary> {
+  const sdk = await import("@cline/sdk");
+  const catalog = sdk.getCoreBuiltinToolCatalog();
+  return {
+    version: sdk.CORE_BUILD_VERSION,
+    tools: catalog.map((entry) => ({
+      id: entry.id,
+      description: entry.description,
+    })),
+  };
+}