Spawn isolated agents for parallel task execution with runtime-native team selection and fresh context per wave.

• ›Auto-selects spawn backend based on runtime: Claude Native Teams in Claude sessions, Codex sub-agents in Codex sessions, or inline fallback if multi-agent unavailable
• ›Executes tasks in dependency-ordered waves, spawning only unblocked tasks in parallel while respecting file ownership conflicts via pre-spawn manifest validation
• ›Implements Ralph Wiggum pattern: fresh worker