feat(patterns): align manual and auto behaviour

Unify manual/auto timing semantics for key patterns, add preset background support, and improve runtime observability while keeping the driver responsive under beat-triggered selects.

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

tests/patterns/twinkle.py

@@ -0,0 +1,52 @@
+#!/usr/bin/env python3
+import utime
+from machine import WDT
+from settings import Settings
+from presets import Presets
+
+
+def main():
+    print("[test] twinkle: start")
+    s = Settings()
+    p = Presets(pin=s.get("led_pin", 10), num_leds=s.get("num_leds", 30))
+    p.debug = True
+    wdt = WDT(timeout=10000)
+
+    print("[test] twinkle: auto phase begin")
+    p.edit("test_pattern", {"p": "twinkle", "b": 64, "a": True, "d": 3000, "c": [(255, 0, 0), (0, 0, 255)]})
+    if not p.select("test_pattern"):
+        raise Exception("twinkle select failed in auto phase")
+    auto_start = utime.ticks_ms()
+    while utime.ticks_diff(utime.ticks_ms(), auto_start) < 2500:
+        wdt.feed()
+        p.run_step()
+        utime.sleep_ms(20)
+    remaining_ms = utime.ticks_diff(p.next_tick_ms, utime.ticks_ms())
+    if p.next_tick_ms == 0 or remaining_ms <= 0:
+        raise Exception("twinkle delay scheduling invalid")
+    print("[test] twinkle: auto phase end")
+
+    print("[test] twinkle: manual phase begin")
+    p.edit("test_pattern", {"p": "twinkle", "b": 64, "a": False, "d": 3000, "c": [(255, 0, 0), (0, 0, 255)]})
+    if not p.select("test_pattern", step=0):
+        raise Exception("twinkle select failed in manual phase")
+    for _ in range(6):
+        current_step = int(p.step)
+        if not p.select("test_pattern", step=current_step):
+            raise Exception("twinkle external select failed")
+        p.run_step()
+        wdt.feed()
+        if int(p.step) == current_step:
+            raise Exception("twinkle external step did not advance")
+        if p.generator is not None:
+            raise Exception("twinkle manual mode rescheduled generator")
+        hold_start = utime.ticks_ms()
+        while utime.ticks_diff(utime.ticks_ms(), hold_start) < 700:
+            wdt.feed()
+            utime.sleep_ms(20)
+    print("[test] twinkle: manual phase end")
+    print("[test] twinkle: pass")
+
+
+if __name__ == "__main__":
+    main()