Claude Code v2.1.142 ships new agent flags; Fast mode now defaults to Opus 4.7

Claude Code v2.1.142 adds a battery of new flags for dispatched background sessions (--add-dir, --settings, --mcp-config, --plugin-dir, --permission-mode, --model, --effort, --dangerously-skip-permissions) and makes Opus 4.7 the default for Fast mode, with an env var to pin back to Opus 4.6.