Migration notes for akm v0.1.0

- The package and project were rebranded from Agent-i-Kit to akm.
- Update package references from `agent-i-kit` to `akm-cli`.
- Update config, registry, plugin, path, and environment-variable references from `agent-i-kit` / `AGENT_I_KIT_*` to `akm` / `AKM_*`.
- The `tool` asset type and `submit` command were removed.
