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

test/rainbow/7.py

@@ -0,0 +1,56 @@
+#!/usr/bin/env python3
+"""
+Rainbow test 7: Twelve nodes (fine gradation), 0.4 second cycle, full brightness
+Runs forever
+Run with: mpremote run test/rainbow/7.py
+"""
+
+import patterns
+import utime
+from settings import Settings
+from machine import WDT
+
+print("Starting Rainbow Test 7: Twelve nodes (fine gradation), 0.4 second cycle")
+print("Press Ctrl+C to stop")
+
+# Load settings
+settings = Settings()
+
+# Initialize patterns using settings
+p = patterns.Patterns(
+    pin=settings["led_pin"], 
+    num_leds=settings["num_leds"], 
+    brightness=255,
+    delay=400  # 0.4 second cycle
+)
+
+# Configure test parameters
+p.n1 = 12           # 12 nodes
+p.delay = 400       # 0.4 second cycle
+p.brightness = 255  # Full brightness
+
+print(f"LED Pin: {settings['led_pin']}")
+print(f"LEDs: {settings['num_leds']}")
+print(f"Brightness: {p.brightness}")
+print(f"Delay: {p.delay}ms")
+print(f"Nodes: {p.n1}")
+
+# Initialize watchdog timer
+wdt = WDT(timeout=10000)
+wdt.feed()
+
+# Start pattern
+p.select("rb")
+print("Pattern started. Running forever...")
+
+# Run forever
+try:
+    while True:
+        wdt.feed()
+        utime.sleep_ms(100)
+except KeyboardInterrupt:
+    print("\nStopping...")
+    p.run = False
+    p.off()
+    print("LEDs turned off")
+