feat!: Migrate to Custom Resources and remove recipes

[damacus]

Summary

• migrate the cookbook from legacy recipe and attribute layout to modern custom resources under resources/
• replace recipe-based unit and integration coverage with resource-focused ChefSpec and InSpec suites
• update Kitchen, CI, docs, and limitations to match the supported package platforms and the new custom-resource workflow

Verification

• cookstyle
• chef exec rspec --format documentation via the embedded Chef Workstation chef-cli path
• kitchen test default-ubuntu-2404
• kitchen test client-ubuntu-2404
• kitchen test server-ubuntu-2404

[github-actions]

Slowest examples

Top 10 slowest examples (1.77 seconds, 84.67% of total time)

Example	Description	Time in seconds
spec/unit/resources/ossec_server_spec.rb:36	ossec_server installs the server package	0.63104
spec/unit/resources/ossec_client_spec.rb:33	ossec_client installs the agent package	0.43626
spec/unit/resources/ossec_repository_spec.rb:27	ossec_repository on debian-13 creates the apt repository as trusted	0.1844
spec/helpers_spec.rb:53	OssecCookbook::Helpers marks Debian 13 repositories as trusted for apt	0.14029
spec/unit/resources/ossec_config_spec.rb:44	ossec_config on rockylinux-9 does not include unsupported use_geoip in ossec.conf	0.12627
spec/unit/resources/ossec_agent_auth_spec.rb:22	ossec_agent_auth runs agent-auth	0.06373
spec/unit/resources/ossec_repository_spec.rb:51	ossec_repository on amazonlinux-2023 uses the Amazon Linux repository path	0.05675
spec/unit/resources/ossec_install_spec.rb:17	ossec_install configures the package repository	0.04955
spec/unit/resources/ossec_local_spec.rb:20	ossec_local installs the server package	0.04678
spec/unit/resources/ossec_local_spec.rb:24	ossec_local creates ossec.conf	0.04378