Fix prototype: calibrate vision for real D2R screenshots, implement orb detection, improve dashboard

- Created debug tool (cmd/debug/main.go) to analyze real D2R screenshots and calibrate HSV ranges
- Fixed HSV color ranges for health/mana orbs based on real screenshot analysis (99.5% and 82% detection rates)
- Replaced ReadBarPercentage with ReadOrbPercentage for circular orbs (not horizontal bars)
- Added SetSource() method to capture Manager for hot-swapping capture sources
- Fixed dashboard JavaScript null reference errors with proper array checks
- Improved dashboard refresh rate from 100ms to 1000ms for better performance
- Added proper error handling for empty/null API responses
- Successfully detecting game state, health (99.5%), and mana (82%) from real D2R screenshot

pkg/engine/vision/vision.go

@@ -174,6 +174,38 @@ func (p *Pipeline) ReadBarPercentage(frame image.Image, barRegion image.Rectangl
 	return float64(filledPixels) / float64(totalPixels)
 }
 
+// ReadOrbPercentage reads a circular orb's fill level by sampling the entire region.
+// This is better for D2R health/mana orbs which are circular, not horizontal bars.
+func (p *Pipeline) ReadOrbPercentage(frame image.Image, orbRegion image.Rectangle, filledColor ColorRange) float64 {
+	bounds := orbRegion.Intersect(frame.Bounds())
+	if bounds.Empty() {
+		return 0.0
+	}
+	
+	totalPixels := 0
+	filledPixels := 0
+	
+	// Sample every pixel in the orb region
+	// For performance, we could sample every 2-3 pixels instead
+	step := 2 // Sample every 2nd pixel for performance
+	for y := bounds.Min.Y; y < bounds.Max.Y; y += step {
+		for x := bounds.Min.X; x < bounds.Max.X; x += step {
+			c := frame.At(x, y)
+			hsv := RGBToHSV(c)
+			totalPixels++
+			if p.colorInRange(hsv, filledColor) {
+				filledPixels++
+			}
+		}
+	}
+	
+	if totalPixels == 0 {
+		return 0.0
+	}
+	
+	return float64(filledPixels) / float64(totalPixels)
+}
+
 // GetPixelColor returns the color at a specific pixel.
 func (p *Pipeline) GetPixelColor(frame image.Image, x, y int) color.Color {
 	return frame.At(x, y)