Remove Orka support and simplify Tart provisioning

[hisaac]

Summary

• Remove Orka tasks, inventory discovery, and VM-provider selection.
• Consolidate Tart packages into the main agent configuration, use the openai/tools tap, and remove the Homebrew wrapper role.
• Rename the provisioning task to provision and generate Tart hostnames with native uuidgen.
• Use four-space Python indentation and update workflow documentation and reference provenance.

Validation

• Ruff lint and formatting checks passed.
• TOML validation and hostname ShellCheck passed.
• Ansible lint passed across 34 files.
• Git diff whitespace checks passed.
• Live Tart provisioning has not been run; actual workflow testing remains the end-to-end verification.