CLI: Compaction Hooks and Session Credits

This release adds PreCompact and PostCompact Hooks that run around conversation compaction, and shows the credits a session has used so far in /usage, the status line, and workflow step rows. It also lets you ship default settings for an environment, adds an opt-in session recap, lets sub-agents read their parent's memories, groups notifications into one row, and fixes rendering, sub-agent, workflow, and headless issues.