Print CLI errors as one line instead of a stack trace (closes #102)

An error a command throws now reaches the user as one `quak: MESSAGE`
line on stderr, and the CLI exits 1 once output has drained. The wrapper
moved from bin/quak.ts to src/cli-run.ts so it can be tested, and
bin/quak.ts awaits program.parseAsync() so async actions are awaited.

Model: opus-5-5

bin/quak.ts

@@ -18,6 +18,7 @@ import {
     listMissingThumbnailsCommand,
     fixMissingThumbnailsCommand,
 } from "../src/cli-commands.js";
+import { run as runCommand } from "../src/cli-run.js";
 import { loadSession } from "../src/cli-session.js";
 import { VERSION } from "../src/index.js";
 
@@ -43,23 +44,8 @@ const context = (): CliContext => ({
     loadSession,
 });
 
-// Run a command and exit with its code once stdout/stderr have drained.
-// Exiting before the drain can truncate piped output, and the library can keep
-// the event loop alive after a command returns, so a plain return could hang.
-const run = async (command: Promise<number>): Promise<void> => {
-    process.exitCode = await command;
-    const pending = [stdout, stderr].filter((s) => s.writableLength > 0);
-    if (pending.length === 0) {
-        process.exit();
-        return;
-    }
-    let remaining = pending.length;
-    for (const s of pending) {
-        s.once("drain", () => {
-            if (--remaining === 0) process.exit();
-        });
-    }
-};
+const run = (command: Promise<number>): Promise<void> =>
+    runCommand(command, stdout, stderr, (code) => process.exit(code));
 
 program
     .command("login")
@@ -169,4 +155,4 @@ helper
     );
 
 await init();
-program.parse();
+await program.parseAsync();