feat: add update command with self-update, verification, and rollback (#391)

scripts/run.js

@@ -9,6 +9,38 @@ const path = require("path");
 const ext = process.platform === "win32" ? ".exe" : "";
 const bin = path.join(__dirname, "..", "bin", "lark-cli" + ext);
 
+// On Windows, a crashed self-update may have left the binary renamed to .old.
+// Recover it before proceeding so the CLI remains functional.
+const oldBin = bin + ".old";
+function restoreOldBinary() {
+  try {
+    if (fs.existsSync(bin)) {
+      fs.rmSync(bin, { force: true });
+    }
+    fs.renameSync(oldBin, bin);
+    return true;
+  } catch (_) {
+    return false;
+  }
+}
+
+if (process.platform === "win32" && fs.existsSync(oldBin)) {
+  if (!fs.existsSync(bin)) {
+    restoreOldBinary();
+  } else {
+    try {
+      execFileSync(bin, ["--version"], { stdio: "ignore", timeout: 10000 });
+      try {
+        fs.rmSync(oldBin, { force: true });
+      } catch (_) {
+        // Best-effort cleanup; keep running the healthy binary.
+      }
+    } catch (_) {
+      restoreOldBinary();
+    }
+  }
+}
+
 if (!fs.existsSync(bin)) {
   console.error(
     `Error: lark-cli binary not found at ${bin}\n\n` +