46 test cases covering:
- clampFloat helper (9 cases: range checks, boundary conditions)
- Staleness score impact (5 cases: 0/0.25/0.5/0.75/1 scores)
- Error penalty (5 cases: 0 to 10 errors, min clamping)
- Queue depth stretching (5 cases: 1 to 50 depth, max clamping)
- EMA smoothing (convergence behavior with alpha=0.6)
- Jitter (bounds checking, deterministic tests with seeded RNG)
- Boundary conditions (6 cases: zero/negative intervals, max<min)
- Combined factors (3 cases: all factors interacting)
- State persistence (per-instance EMA state isolation)
First unit test file for scheduler.go (previously only had integration tests).
