feat: Aether-Link Adaptive DSP Controller (Score: 84.45)

[teerthsharma]

## Aether Adaptive DSP Controller (`controllers/aether.py`)

**Cost reduction:** `106.8` → `84.45` (-20.9%)

### How it works
- **Variance (σ²)** – Welford’s running variance (tracks instability)  
- **Chebyshev spectral energy (C)** – RMS of delta-differences (noise detection)  

Adaptive gain squashing:  
`P_adapt ∝ 1 / (1 + ασ² + βC)` → eliminates over‑correction, slashes jerk.

### Performance (100 segments)
| Controller | Total cost |
|------------|-------------|
| Baseline PID | 106.8 |
| **Aether DSP** | **84.45** |

### Jerk minimisation

LatAccel Error
^
| /\ / [PID] overshoots
| / \ /\ /
| / / /
| / --- [AETHER] smooth
|/ -- --__
+------------------> Time