feat: add fan curve control via temperature-based fan speed curves

- Backend HAL (hal/fans.py): NVML v2 fan read/set/reset with min/max queries
- Server endpoints: GET/POST /api/fans, POST /api/fans/reset, POST /api/fans/speed
- Background fan poller: reads GPU temp every 2s, interpolates fan speed from curve
- Profile integration: fan_curve field saved/applied, auto-restore on shutdown
- Frontend: FanCurveEditor (SVG chart with drag/add/delete points), FanMonitor sidebar
- App.tsx: three-tab layout (Curve, Performance, Fans)
- GaugeCard: optional history sparkline, Fan Mode card without sparkline
- fan_mode field populated as 'curve' or 'auto' in GET /api/fans

uv.lock

@@ -156,7 +156,7 @@ wheels = [
 
 [[package]]
 name = "nvcurve"
-version = "0.5.0"
+version = "0.5.1"
 source = { editable = "." }
 dependencies = [
     { name = "fastapi" },