Extract setup profiles helper

[codeforester]

Summary

• add setup_profiles.sh for setup/check profile parsing and dispatch helpers
• keep existing public setup_* names while setup_common.sh sources the profile helper and keeps shared orchestration
• update setup-common ownership docs and source-guard coverage for the new helper

Refs #1570

Validation

• /Users/rameshhp/.base.d/base/.venv/bin/python -m pytest tests/test_setup_common_ownership_docs.py tests/test_contract_hardening.py -q
• BASE_BASH_LIBS_DIR=/Users/rameshhp/work/base-bash-libs/lib/bash bats cli/bash/commands/basectl/tests/setup-common.bats
• bash -n cli/bash/commands/basectl/subcommands/setup_common.sh cli/bash/commands/basectl/subcommands/setup_linux_debian.sh cli/bash/commands/basectl/subcommands/setup_macos_homebrew.sh cli/bash/commands/basectl/subcommands/setup_venv.sh cli/bash/commands/basectl/subcommands/setup_profiles.sh
• shellcheck -S error cli/bash/commands/basectl/subcommands/setup_common.sh cli/bash/commands/basectl/subcommands/setup_linux_debian.sh cli/bash/commands/basectl/subcommands/setup_macos_homebrew.sh cli/bash/commands/basectl/subcommands/setup_venv.sh cli/bash/commands/basectl/subcommands/setup_profiles.sh
• /Users/rameshhp/.base.d/base/.venv/bin/python -m pylint --rcfile=.pylintrc tests/test_setup_common_ownership_docs.py
• git diff --check
• env BASE_BASH_LIBS_DIR=/Users/rameshhp/work/base-bash-libs/lib/bash BASE_CACHE_DIR=/private/tmp/base-1570-profiles-helper bin/basectl setup --profile dev --dry-run
• env BASE_BASH_LIBS_DIR=/Users/rameshhp/work/base-bash-libs/lib/bash BASE_CACHE_DIR=/private/tmp/base-1570-profiles-helper bin/basectl check --ci
• env -u BASE_HOME BASE_BASH_LIBS_DIR=/Users/rameshhp/work/base-bash-libs/lib/bash BASE_CACHE_DIR=/private/tmp/base-1570-profiles-helper-full ./bin/base-test