Module scheduler 

Real-time audio scheduler.

This is the hot path. It:

1. Drains bounded commands from the SPSC ring.
2. Executes the topologically sorted node list level by level. Nodes within the same BFS level are independent and run in parallel via Rayon’s work-stealing thread pool.
3. Copies the output node’s buffer to the DAC output.

HARD RT RULES enforced here:

• No allocation (Vec is pre-allocated per level, bounded by MAX_NODES)
• No locks
• No I/O
• No unbounded loops

Structs

Scheduler

The RT scheduler. Owns the graph and processes audio callbacks.