Add compaction.md and rewrite hooks.md
- New compaction.md covers auto-compaction and branch summarization - Explains cut points, split turns, data model, file tracking - Documents session_before_compact and session_before_tree hooks - Rewritten hooks.md matches actual API (separate event names) - Correct ctx.ui.custom() signature (returns handle, not callback) - Documents all session events including tree events - Adds sessionManager and modelRegistry usage - Updates all examples to use correct API
This commit is contained in: