fix(hint): explain that "--force" option exists (#746)

Fixes #624

When the `occ app_api:app:unregister` command fails to remove a
container (e.g., because it was already deleted manually), users are now
shown a helpful hint suggesting the `--force` option to continue
unregistering.

The hint includes the container name for easier manual
verification/cleanup.

Before:
```
  Failed to remove ExApp my_ex_app container
```

After:
```
  Failed to remove ExApp my_ex_app container
  Hint: If the container "nc_app_my_ex_app" was already removed manually, you can use the --force option to continue unregistering.
  
```

---------

Signed-off-by: Oleksander Piskun <[email protected]>
Signed-off-by: Oleksandr Piskun <[email protected]>
Co-authored-by: Anupam Kumar <[email protected]>

Author: oleksandr-nc

lib/Command/ExApp/Unregister.php

@@ -102,6 +102,7 @@ protected function execute(InputInterface $input, OutputInterface $output): int
 				if ($this->dockerActions->removeExApp($this->dockerActions->buildDockerUrl($daemonConfig), $exApp->getAppid(), removeData: $rmData)) {
 					if (!$silent) {
 						$output->writeln(sprintf('Failed to remove ExApp %s', $appId));
+						$output->writeln('Hint: If the container was already removed manually, you can use the --force option to fully remove it from AppAPI.');
 					}
 					if (!$force) {
 						return 1;
@@ -112,12 +113,14 @@ protected function execute(InputInterface $input, OutputInterface $output): int
 					}
 				}
 			} else {
+				$containerName = $this->dockerActions->buildExAppContainerName($appId);
 				$removeResult = $this->dockerActions->removeContainer(
-					$this->dockerActions->buildDockerUrl($daemonConfig), $this->dockerActions->buildExAppContainerName($appId)
+					$this->dockerActions->buildDockerUrl($daemonConfig), $containerName
 				);
 				if ($removeResult) {
 					if (!$silent) {
 						$output->writeln(sprintf('Failed to remove ExApp %s container', $appId));
+						$output->writeln(sprintf('Hint: If the container "%s" was already removed manually, you can use the --force option to fully remove it from AppAPI.', $containerName));
 					}
 					if (!$force) {
 						return 1;