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/capture/capture.go

@@ -107,3 +107,23 @@ func (m *Manager) Source() Source {
 func (m *Manager) Size() (width, height int) {
 	return m.source.Size()
 }
+
+// SetSource swaps the capture source.
+// This is useful for development when uploading new screenshots.
+func (m *Manager) SetSource(newSource Source) error {
+	// Close the old source
+	if m.source != nil {
+		if err := m.source.Close(); err != nil {
+			// Log but don't fail - we still want to switch sources
+			// log.Printf("Warning: failed to close old capture source: %v", err)
+		}
+	}
+	
+	// Switch to new source
+	m.source = newSource
+	
+	// Reset stats for the new source
+	m.stats = Stats{}
+	
+	return nil
+}