Refactor rainbow pattern to travel along the length of LED strip

- Modified rainbow() to distribute colors along the physical length
- Each LED gets a different hue based on its position
- n1 parameter controls how many times the rainbow cycles (nodes)
- Split rainbow tests into test/rainbow/ directory with 9 numbered test files
- Each test runs forever until interrupted
- Added main.py to run all tests in sequence repeatedly

src/patterns.py

@@ -209,13 +209,14 @@ class Patterns(PatternBase): # Inherit from PatternBase
                 # Clear all LEDs
                 self.n.fill((0, 0, 0))
                 
-                # Create rainbow effect with n1 nodes
+                # Rainbow travels along the length - distribute colors along the strip
                 for i in range(self.num_leds):
-                    # Calculate hue based on LED position, number of nodes, and time
-                    hue_per_node = 360 // num_nodes
-                    node_index = i * num_nodes // self.num_leds
-                    base_hue = node_index * hue_per_node
-                    hue = (base_hue + self.step) % 360
+                    # Calculate hue based on LED position along the strip
+                    # Distribute full 360 degrees across the strip, repeat num_nodes times
+                    # Position along the strip (0.0 to 1.0)
+                    position = i / self.num_leds
+                    # Hue cycles based on position and number of nodes
+                    hue = int((position * 360 * num_nodes + self.step) % 360)
                     
                     # Convert HSV to RGB
                     rgb = self.hsv_to_rgb(hue, 255, self.brightness)