feat(patterns): merge pattern styles and add mode support

Consolidate legacy pattern ids into meteor, particles, sparkle, chase,
and colour_cycle with n6/mode style selection; add pattern_modes helper,
self-contained tests/all.py, and preset mode alias on wire.

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

src/patterns/particles.py

@@ -0,0 +1,108 @@
+import random
+import utime
+
+from patterns.pattern_modes import style_mode
+
+_LEGACY = {"starfall": 1}
+
+
+class Particles:
+    def __init__(self, driver):
+        self.driver = driver
+
+    def _run_snowfall(self, preset, colors, flakes, last):
+        density = max(1, int(preset.n1) if int(preset.n1) > 0 else 20)
+        speed = max(1, int(preset.n2) if int(preset.n2) > 0 else 1)
+        d = max(1, int(preset.d))
+        now = utime.ticks_ms()
+        if utime.ticks_diff(now, last) < d:
+            return flakes, last, False
+        bg_color = self.driver.apply_brightness(preset.background_or(colors), preset.b)
+        if random.randint(0, 255) < density:
+            flakes.append([self.driver.num_leds - 1, random.randint(0, len(colors) - 1)])
+        for i in range(self.driver.num_leds):
+            self.driver.n[i] = bg_color
+        nf = []
+        for pos, ci in flakes:
+            if 0 <= pos < self.driver.num_leds:
+                self.driver.n[pos] = self.driver.apply_brightness(colors[ci], preset.b)
+            pos -= speed
+            if pos >= -1:
+                nf.append([pos, ci])
+        self.driver.n.write()
+        return nf, utime.ticks_add(last, d), True
+
+    def _run_starfall(self, preset, colors, stars, last):
+        rate = max(1, min(255, int(preset.n1) if int(preset.n1) > 0 else 14))
+        speed = max(1, int(preset.n2) if int(preset.n2) > 0 else 2)
+        tail = max(2, int(preset.n3) if int(preset.n3) > 0 else 10)
+        max_stars = 4
+        d = max(1, int(preset.d))
+        now = utime.ticks_ms()
+        if utime.ticks_diff(now, last) < d:
+            return stars, last, False
+        bg = self.driver.apply_brightness(preset.background_or(colors), preset.b)
+        for i in range(self.driver.num_leds):
+            self.driver.n[i] = bg
+        if len(stars) < max_stars and random.randint(0, 255) < rate:
+            top = self.driver.num_leds - 1 + random.randint(
+                0, min(8, self.driver.num_leds // 2)
+            )
+            stars.append({"h": float(top), "ci": random.randint(0, len(colors) - 1)})
+        ns = []
+        for s in stars:
+            h = s["h"]
+            ci = s["ci"]
+            ih = int(h)
+            for t in range(tail):
+                idx = ih + t
+                if 0 <= idx < self.driver.num_leds:
+                    fade = 255 - (t * 255 // max(1, tail - 1))
+                    base = colors[ci]
+                    lit = (
+                        (base[0] * fade) // 255,
+                        (base[1] * fade) // 255,
+                        (base[2] * fade) // 255,
+                    )
+                    lit = self.driver.apply_brightness(lit, preset.b)
+                    o = self.driver.n[idx]
+                    self.driver.n[idx] = (
+                        max(o[0], lit[0]),
+                        max(o[1], lit[1]),
+                        max(o[2], lit[2]),
+                    )
+            h -= speed
+            if h >= -tail:
+                s["h"] = h
+                ns.append(s)
+        stars = ns
+        self.driver.n.write()
+        return stars, utime.ticks_add(last, d), True
+
+    def run(self, preset):
+        """Falling particles: n6 0 snowfall flakes, 1 starfall streaks."""
+        mode = style_mode(preset, 0, _LEGACY)
+        colors = preset.c if preset.c else [(255, 255, 255), (180, 220, 255)]
+        last = utime.ticks_ms()
+
+        if mode == 1:
+            colors = preset.c if preset.c else [
+                (255, 255, 255),
+                (200, 230, 255),
+                (255, 248, 220),
+            ]
+            stars = []
+            while True:
+                stars, last, stepped = self._run_starfall(preset, colors, stars, last)
+                if stepped and not preset.a:
+                    yield
+                    return
+                yield
+
+        flakes = []
+        while True:
+            flakes, last, stepped = self._run_snowfall(preset, colors, flakes, last)
+            if stepped and not preset.a:
+                yield
+                return
+            yield