chore: migrate dependency resolution to Policyfile

[damacus]

Summary

• migrate dependency resolution from Berksfile to Policyfile
• update ChefSpec setup to use Policyfile resolution
• update CI/Copilot workflow references to current sous-chefs workflow/action versions
• move cookbook limitations into AGENTS.md where present

Verification

• chef install Policyfile.rb
• cookstyle
• /opt/chef-workstation/embedded/bin/rspec --format progress
• kitchen list

[github-actions]

Slowest examples

Top 10 slowest examples (0.75 seconds, 56.02% of total time)

Example	Description	Time in seconds
spec/unit/resources/cacher_client_spec.rb:18	apt_cacher_client without a cache server is expected to delete file "/etc/apt/apt.conf.d/01proxy"	0.12857
spec/unit/resources/unattended_upgrades_spec.rb:17	apt_unattended_upgrades is expected to create directory "/var/cache/local/preseeding"	0.12425
spec/unit/resources/cacher_ng_spec.rb:21	apt_cacher_ng is expected to render file "/etc/apt-cacher-ng/acng.conf"	0.11752
spec/unit/resources/unattended_upgrades_spec.rb:22	apt_unattended_upgrades is expected to render file "/etc/apt/apt.conf.d/50unattended-upgrades"	0.05926
spec/unit/resources/cacher_ng_spec.rb:19	apt_cacher_ng is expected to render file "/etc/apt-cacher-ng/acng.conf"	0.05686
spec/unit/resources/cacher_ng_spec.rb:20	apt_cacher_ng is expected to render file "/etc/apt-cacher-ng/acng.conf"	0.05638
spec/unit/resources/config_spec.rb:22	apt_config is expected to render file "/etc/apt/apt.conf.d/10recommends"	0.05431
spec/unit/resources/cacher_client_spec.rb:36	apt_cacher_client with a cache server is expected to render file "/etc/apt/apt.conf.d/01proxy"	0.0534
spec/unit/resources/cacher_client_spec.rb:37	apt_cacher_client with a cache server is expected to render file "/etc/apt/apt.conf.d/01proxy"	0.05279
spec/unit/resources/unattended_upgrades_spec.rb:21	apt_unattended_upgrades is expected to render file "/etc/apt/apt.conf.d/20auto-upgrades"	0.05192