Update pattern tests for new preset-based API

- Replace add() calls with edit() for preset creation
- Update tests to work with merged patterns.py
- Ensure all tests use new Preset object structure

test/patterns/off.py

@@ -14,7 +14,7 @@ def main():
     wdt = WDT(timeout=10000)
     
     # Create an "off" preset
-    p.add("test_off", {"pattern": "off"})
+    p.edit("test_off", {"pattern": "off"})
     p.select("test_off")
 
     start = utime.ticks_ms()