Re-implements work that was lost due to ephemeral source/ subdirectory.
ITR dynamically adjusts interrupt coalescing based on packet rate.
- Add ITR register (0xC4) and set_itr() to device.rs
- Add itr.rs tracker with hysteresis-based rate adaptation
- Wire tracker into IRQ handler in main.rs
- Document in AGENTS.md: source/ is ALWAYS rewritten
vasilito
0046c76e43