fix: migrate to Policyfile and map Kitchen suites

[damacus]

Summary

• replace Berksfile dependency resolution with Policyfile.rb
• switch ChefSpec setup to Policyfile support where applicable
• update Copilot setup/docs away from berks install
• keep Policyfile.lock.json generated locally and ignored

Verification

• chef install Policyfile.rb
• /opt/homebrew/bin/markdownlint-cli2 "**/*.md"
• cookstyle --no-server --cache-root /private/tmp/rubocop_cache
• chef exec rspec --format documentation equivalent via Workstation embedded RSpec
• KITCHEN_LOCAL_YAML=kitchen.dokken.yml kitchen test default-debian-12 --destroy=always

[github-actions]

Slowest examples

Top 10 slowest examples (0.68 seconds, 91.98% of total time)

Example	Description	Time in seconds
spec/unit/resources/client_spec.rb:52	git_client on windows is expected to install windows_package "Git version 2.54.0"	0.10851
spec/unit/resources/client_spec.rb:15	git_client on ubuntu is expected to install package "default :install git"	0.08058
spec/unit/resources/client_spec.rb:28	git_client from source on ubuntu is expected to install build_essential "install compilation tools for git"	0.07167
spec/unit/resources/client_spec.rb:65	git_client remove on ubuntu is expected to remove package "default :remove git"	0.06767
spec/unit/resources/client_spec.rb:30	git_client from source on ubuntu is expected to install_with_make ark "git"	0.06276
spec/unit/resources/client_spec.rb:29	git_client from source on ubuntu is expected to install package "["libcurl4-gnutls-dev", "libexpat1-dev", "gettext", "libz-dev", "libssl-dev"]"	0.06046
spec/unit/resources/config_spec.rb:23	git_config set a global value is expected to run execute "git config --global user.name "Jane Doe""	0.05919
spec/unit/resources/client_spec.rb:40	git_client on macos is expected to install package "default :install git"	0.05918
spec/unit/resources/config_spec.rb:34	git_config unset a system value is expected to run execute "git config --system --unset-all user.name"	0.05714
spec/unit/resources/config_spec.rb:51	git_config set a file-scoped value with a home-relative config path is expected to run execute "git config --file "/root/.gitconfig.key" user.signingkey "FA2D8E280A6DD5""	0.05425