ci: explicitly exit Node lint scripts to fix CI hang (#22794)

The three Node scripts that run under `setup-node` (lint-lockfile,
lint-runtime, setup-corepack) finish their main work but the Node
process does not exit — the event loop is kept alive by an outstanding
handle from one of the upstream libraries. In CI this causes the step
to hang indefinitely until the runner timeout fires.

Add an explicit `process.exit(0)` after the success path in each
script. setup-corepack is restructured so `main()` returns the
`$`corepack …`` promise and the success log moves into `.then()`
before the exit, keeping ordering deterministic.

Co-authored-by: Agent (authentik-m-split-pr-committed-every-mikado) <279763771+playpen-agent@users.noreply.github.com>

scripts/node/lint-lockfile.mjs

@@ -274,5 +274,7 @@ run()
         } else {
             logger.info("✅ Lockfile is in sync.");
         }
+
+        process.exit(0);
     })
     .catch((error) => reportAndExit(error, logger));

scripts/node/lint-runtime.mjs

@@ -110,5 +110,6 @@ async function main() {
 main()
     .then(() => {
         logger.info("✅ Node.js and npm versions are in sync.");
+        process.exit(0);
     })
     .catch((error) => reportAndExit(error, logger));

scripts/node/setup-corepack.mjs

@@ -102,9 +102,12 @@ async function main() {
         subcommand = "use";
     }
 
-    await $`corepack ${subcommand} ${packageManager}`({ cwd });
-
-    logger.info("Corepack installed npm successfully");
+    return $`corepack ${subcommand} ${packageManager}`({ cwd });
 }
 
-main().catch((error) => reportAndExit(error, logger));
+main()
+    .then(() => {
+        logger.info("Corepack setup completed successfully");
+        process.exit(0);
+    })
+    .catch((error) => reportAndExit(error, logger));