fix(traefik): preserve remote YAML shell quotes

[yusoofsh]

Summary

• write remote Traefik YAML via a base64 payload instead of single-quoted echo
• preserve shell-sensitive YAML values such as CSP keywords ('unsafe-inline', 'self', 'none')
• add a regression test that decodes the generated remote command payload and asserts the quotes survive

Why

writeTraefikConfigRemote currently serializes YAML and sends it through:

echo '${yaml}' > ${configPath}

If the YAML contains single quotes, the remote shell consumes them before writing the file. This corrupts valid values such as Content-Security-Policy directives.

Verification

• git diff --check
• Node self-check confirmed the base64 command decodes to a CSP value containing 'unsafe-inline' and 'self'

Could not run the focused Vitest/Biome checks locally because dependency installation failed before dev binaries were available:

ERR_NUB_TRUST_DOWNGRADE for @octokit/plugin-paginate-rest@9.2.2