v0.5.0

Added

• Release archives now publish checksums.txt, and the README documents shell
  completion generation.
• orc doctor --system checks install readiness outside a workspace, including
  version, PATH visibility, optional tools, tmux, chafa, and supported agent
  CLIs.
• orc pack inspect <path> validates and previews local workflow packs without installing them.
• orc init --pack <path> can scaffold a workspace from one local workflow pack.
• orc init --skip-default-pack creates the base scaffold without installing the default pack.
• orc pack install <pack> installs a built-in pack name or local pack path into an existing workspace.
• orc pack list and orc pack show <pack> report install provenance and active workflows.
• Pack composition checks now reject duplicate workflow IDs, duplicate worker
  IDs, duplicate stage IDs, and conflicting aliases before install.
• Generated workspaces now install the built-in default pack with aliases and a
  consistent namespaced runtime layout under stages/<pack>/ and workers/<pack>/.

Changed

• Makefile Go targets now use repo-local cache directories by default, avoiding
  home-cache permission failures in sandboxed runs.
• Pack documentation now clarifies embedded packs, installed snapshots, local
  path packs, workspace-owned files, and the roles of inspect, install,
  list, and show.