feat(uno-q): add bloom, breathe, checker effects to the matrix sampler

Rounds out the sampler with the remaining effects:
- bloom   — a filled diamond grows from the centre to full, then collapses.
- breathe — a dithered shimmer that swells and fades (density ramp via a
            fixed per-pixel threshold, since the matrix can't truly fade).
- checker — a checkerboard that inverts on each beat.

Full cycle is now rain -> knight-rider -> comet -> ripple -> bloom ->
breathe -> sparkle -> checker -> wipe. Compiled + flashed E2E (2057 bytes).

Co-Authored-By: Claude Opus 4.8 <[email protected]>

deploy/uno-q/sketches/README.md

@@ -7,7 +7,7 @@ Animations for the Arduino Uno Q's built-in **13×8 monochrome blue** LED matrix
 | Sketch | What it does |
 |--------|--------------|
 | `matrix_rain/` | Digital "rain" — per-column drops (head + short trail) at staggered speeds. |
-| `matrix_effects/` | Sampler that cycles rain → knight-rider sweep → comet → ripple → sparkle → wipe. |
+| `matrix_effects/` | Sampler that cycles rain → knight-rider → comet → ripple → bloom → breathe → sparkle → checker → wipe. |
 
 ## How they work
 

deploy/uno-q/sketches/matrix_effects/matrix_effects.ino

@@ -1,6 +1,7 @@
 // Matrix animation sampler for the Arduino Uno Q's 13x8 blue LED matrix.
 // Cycles through several frame-based effects: rain -> knight-rider sweep ->
-// comet -> ripple -> sparkle -> wipe, then repeats. All monochrome (pixels are on/off;
+// comet -> ripple -> bloom -> breathe -> sparkle -> checker -> wipe, then
+// repeats. All monochrome (pixels are on/off;
 // the LEDs are physically blue — there is no colour or brightness control).
 //
 // Shared pattern: each effect fills the 8x13 `grid`, then show() packs it into
@@ -139,6 +140,54 @@ void comet(uint16_t frames) {
   }
 }
 
+// --- bloom: a filled diamond grows from the centre to full, then collapses ---
+void bloom(uint8_t reps) {
+  const int cx = 6, cy = 3;
+  for (uint8_t r0 = 0; r0 < reps; r0++) {
+    for (uint8_t dir = 0; dir < 2; dir++) {
+      for (int r = 0; r <= 8; r++) {
+        int rad = dir ? (8 - r) : r;
+        clearGrid();
+        for (int y = 0; y < H; y++)
+          for (int x = 0; x < W; x++)
+            if (max(abs(x - cx), abs(y - cy)) <= rad) grid[y][x] = true;
+        show(80);
+      }
+    }
+  }
+}
+
+// --- breathe: a dithered shimmer whose density swells and fades (no true fade,
+//     so we ramp how many pixels are lit via a fixed per-pixel threshold) ---
+void breathe(uint8_t breaths) {
+  static uint8_t thr[H][W];
+  for (uint8_t y = 0; y < H; y++)
+    for (uint8_t x = 0; x < W; x++) thr[y][x] = random(0, 100);
+  for (uint8_t b = 0; b < breaths; b++) {
+    for (uint8_t dir = 0; dir < 2; dir++) {
+      for (int s = 0; s <= 100; s += 8) {
+        int level = dir ? (100 - s) : s;
+        clearGrid();
+        for (uint8_t y = 0; y < H; y++)
+          for (uint8_t x = 0; x < W; x++)
+            if (thr[y][x] < level) grid[y][x] = true;
+        show(45);
+      }
+    }
+  }
+}
+
+// --- checker: a checkerboard that inverts on each beat ---
+void checker(uint8_t flips) {
+  for (uint8_t p = 0; p < flips; p++) {
+    clearGrid();
+    for (uint8_t y = 0; y < H; y++)
+      for (uint8_t x = 0; x < W; x++)
+        if (((x + y + p) & 1) == 0) grid[y][x] = true;
+    show(250);
+  }
+}
+
 void setup() {
   matrix.begin();
   randomSeed(micros());
@@ -149,6 +198,9 @@ void loop() {
   knight(2);
   comet(120);
   ripple(2);
+  bloom(2);
+  breathe(2);
   sparkle(40);
+  checker(6);
   wipe(2);
 }