chore: migrate dependency resolution to Policyfile

[damacus]

Summary

• migrate dependency resolution from Berksfile to Policyfile
• update ChefSpec setup to use Policyfile resolution
• update Copilot setup to install Chef Workstation 8.0.4 and run chef install Policyfile.rb
• move cookbook limitations into AGENTS.md where present

Verification

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

[github-actions]

Slowest examples

Top 10 slowest examples (0.79 seconds, 30.57% of total time)

Example	Description	Time in seconds
spec/unit/resources/install_spec.rb:64	control_groups_install when runtime management is disabled is expected to enable systemd_unit "cgred.service"	0.15566
spec/unit/resources/install_spec.rb:25	control_groups_install on ubuntu 24.04 is expected to start systemd_unit "cgred.service"	0.11489
spec/unit/resources/entry_spec.rb:19	control_groups_entry when creating an entry is expected to install package "cgroup-tools"	0.10965
spec/unit/resources/entry_spec.rb:48	control_groups_entry when runtime management is disabled is expected not to start systemd_unit "cgconfig.service"	0.10153
spec/unit/resources/rule_spec.rb:63	control_groups_rule when runtime management is disabled is expected to create systemd_unit "cgred.service"	0.0555
spec/unit/resources/install_spec.rb:62	control_groups_install when runtime management is disabled is expected not to start systemd_unit "cgconfig.service"	0.05224
spec/unit/resources/install_spec.rb:48	control_groups_install action :remove is expected to remove package "libpam-cgroup"	0.05207
spec/unit/resources/rule_spec.rb:60	control_groups_rule when runtime management is disabled is expected to create systemd_unit "cgconfig.service"	0.05154
spec/unit/resources/install_spec.rb:44	control_groups_install action :remove is expected to delete file "/etc/cgconfig.conf"	0.04974
spec/unit/resources/rule_spec.rb:65	control_groups_rule when runtime management is disabled is expected not to start systemd_unit "cgred.service"	0.04898