Add preset persistence and startup default.

Co-authored-by: Cursor <cursoragent@cursor.com>

test/test_espnow_receive.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python3
 """Test ESPNow receive functionality - runs on MicroPython device."""
 import json
+import os
 import utime
 from settings import Settings
 from presets import Presets
@@ -621,6 +622,45 @@ def test_select_with_step():
     print("  ✓ Step set correctly when switching presets")
 
 
+def test_preset_save_load():
+    """Test saving and loading presets to/from JSON."""
+    print("\nTest 10: Preset save/load")
+    settings = Settings()
+    patterns = Presets(settings["led_pin"], settings["num_leds"])
+    
+    patterns.edit("saved_preset", {
+        "p": "blink",
+        "d": 150,
+        "b": 200,
+        "c": [(1, 2, 3), (4, 5, 6)],
+        "a": False,
+        "n1": 1,
+        "n2": 2,
+        "n3": 3,
+        "n4": 4,
+        "n5": 5,
+        "n6": 6,
+    })
+    assert patterns.save(), "Save should return True"
+
+    reloaded = Presets(settings["led_pin"], settings["num_leds"])
+    assert reloaded.load(), "Load should return True"
+    
+    preset = reloaded.presets.get("saved_preset")
+    assert preset is not None, "Preset should be loaded"
+    assert preset.p == "blink", "Pattern should be blink"
+    assert preset.d == 150, "Delay should be 150"
+    assert preset.b == 200, "Brightness should be 200"
+    assert preset.c == [(1, 2, 3), (4, 5, 6)], "Colors should be restored as tuples"
+    assert preset.a is False, "Auto should be False"
+    assert (preset.n1, preset.n2, preset.n3, preset.n4, preset.n5, preset.n6) == (1, 2, 3, 4, 5, 6), "n1-n6 should match"
+    try:
+        os.remove("presets.json")
+    except OSError:
+        pass
+    print("  ✓ Preset save/load works correctly")
+
+
 def main():
     """Run all tests."""
     print("=" * 60)
@@ -637,6 +677,7 @@ def main():
         test_switch_presets()
         test_beat_functionality()
         test_select_with_step()
+        test_preset_save_load()
         
         print("\n" + "=" * 60)
         print("All tests passed! ✓")