feat(tests): add Deno-based tests for checking CLI functionality in the same-codebase between platforms.

src/apps/cli/testdeno/helpers/temp.ts

@@ -0,0 +1,33 @@
+import { join } from "@std/path";
+
+/**
+ * A temporary directory that cleans itself up via `await using`.
+ * Requires TypeScript 5.2+ / Deno 1.40+ for the AsyncDisposable protocol.
+ *
+ * @example
+ * ```ts
+ * await using tmp = await TempDir.create();
+ * const file = tmp.join("data.json");
+ * ```
+ */
+export class TempDir implements AsyncDisposable {
+    readonly path: string;
+
+    private constructor(path: string) {
+        this.path = path;
+    }
+
+    static async create(prefix = "livesync-deno-test"): Promise<TempDir> {
+        const path = await Deno.makeTempDir({ prefix: `${prefix}.` });
+        return new TempDir(path);
+    }
+
+    /** Return an OS path joined to the temp directory root. */
+    join(...parts: string[]): string {
+        return join(this.path, ...parts);
+    }
+
+    async [Symbol.asyncDispose](): Promise<void> {
+        await Deno.remove(this.path, { recursive: true }).catch(() => {});
+    }
+}