Replace vulnerable heredoc patterns across 27 continue.sh scripts with
setup_continue_config() helper that uses json_escape() + upload_config_file()
to safely handle API keys containing special characters like quotes or braces.
Also fix _save_token_to_config() in shared/common.sh which had the same
unescaped heredoc vulnerability for local token storage.
Relates to #104
Agent: security-auditor
Co-authored-by: A <6723574+louisgv@users.noreply.github.com>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>