Mino chapter-14

Added

• Chapter 14 subagent delegation: the spawn_agent tool takes 1 to 10 tasks and runs
  each as a child Agent with its own context, its own session log under
  ~/.mino/sessions/<session_id>.agents/, its own 8-request and 16-call limits, and
  its own compaction. Children share the session's permission mode, tools (except
  spawn_agent and memory_save), skill catalog, and the turn's memory index, and
  run at most 3 at a time, or max_concurrent_subagents (1 to 10) from
  ~/.mino/config.json.
• The parent receives one tool result with each task's status and final text, in
  task order, within a shared 48 KiB budget; the subagents' own tool output never
  enters its context. spawn_agent asks in manual and accept-edits modes, each
  subagent's calls are checked and confirmed separately, one question at a time and
  labelled with the subagent, and a turn may start at most 16 subagents. Parent
  history stays version 4.
• Eval replay cases subagent-batch and subagent-approval; replay runs subagents
  one at a time, and token totals include subagent requests.
• The default SOUL.md explains spawn_agent; existing ~/.mino/SOUL.md files are
  not changed.

Changed

• The OS sandbox now blocks reading and writing ~/.mino, which holds the API key,
  conversations, and memories, for Bash and sandboxed stdio MCP servers. The
  confirmation's sandbox line says so.
• /clear also deletes the cleared session's subagent logs.