Fix --container-id to produce log output

[airblade]

In order to pipe echo into xargs the command needs to run under a shell.

Fixes #1841

[Copilot]

Pull request overview

This PR fixes kamal app logs --container-id so the provided container ID is emitted from a shell command before being piped into xargs docker logs, matching how the rest of the command pipeline is executed.

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Changes:

• Wrap string/symbol container_id values in sh -c before piping to xargs.
• Update command-level expectations for logs and follow_logs to reflect the new shell-wrapped form.
• Update CLI follow-log test coverage for the adjusted SSH command quoting.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
lib/kamal/commands/app/logging.rb	Fixes command construction for explicit container IDs so piped log retrieval works.
test/commands/app_test.rb	Updates low-level command output expectations for log commands using container_id.
test/cli/app_test.rb	Updates CLI follow-log expectation to match the new shell-wrapped SSH command.

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[airblade]

BTW the CI test failures are nothing to do with this change.