fix: ensure CLI exits after command completion (#12906)

* fix: ensure CLI exits after command completion

The CLI process would hang indefinitely after commands like
`openclaw gateway restart` completed successfully.  Two root causes:

1. `runCli()` returned without calling `process.exit()` after
   `program.parseAsync()` resolved, and Commander.js does not
   force-exit the process.

2. `daemon-cli/register.ts` eagerly called `createDefaultDeps()`
   which imported all messaging-provider modules, creating persistent
   event-loop handles that prevented natural Node exit.

Changes:
- Add `flushAndExit()` helper that drains stdout/stderr before calling
  `process.exit()`, preventing truncated piped output in CI/scripts.
- Call `flushAndExit()` after both `tryRouteCli()` and
  `program.parseAsync()` resolve.
- Remove unnecessary `void createDefaultDeps()` from daemon-cli
  registration — daemon lifecycle commands never use messaging deps.
- Make `serveAcpGateway()` return a promise that resolves on
  intentional shutdown (SIGINT/SIGTERM), so `openclaw acp` blocks
  `parseAsync` for the bridge lifetime and exits cleanly on signal.
- Handle the returned promise in the standalone main-module entry
  point to avoid unhandled rejections.

Fixes #12904

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix: refactor CLI lifecycle and lazy outbound deps (#12906) (thanks @DrCrinkle)

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Co-authored-by: Peter Steinberger <steipete@gmail.com>

src/cli/daemon-cli/register.ts

@@ -1,7 +1,6 @@
 import type { Command } from "commander";
 import { formatDocsLink } from "../../terminal/links.js";
 import { theme } from "../../terminal/theme.js";
-import { createDefaultDeps } from "../deps.js";
 import {
   runDaemonInstall,
   runDaemonRestart,
@@ -83,7 +82,4 @@ export function registerDaemonCli(program: Command) {
     .action(async (opts) => {
       await runDaemonRestart(opts);
     });
-
-  // Build default deps (parity with other commands).
-  void createDefaultDeps();
 }