Clarify request timing metrics.

⛰️ Features

• (sdk) Clarify request timing metrics (#738)
• (tui) Scrollable PTY panes (host scrollback + mouse forwarding) (#734)
• (tui) Wire MCP and skills gateways into harnesses (#732)
• (tui) Composite manager (#715)

🐛 Bug Fixes

• (fleet) Non-blocking spawn/prompt so long turns don't time out (#737)
• (sdk) Isolate protocol request extras (#733)

🚜 Refactor

• (tui) Split state.rs into a state/ module (#730)