Initial commit — Amirine Cosplay Lights

Arduino Uno + WS2812B LED strip controller with a text-based lightshow
system. Shows are defined as .txt files (hex color + fade duration per step),
converted to PROGMEM headers by convert_all.py, and navigated at runtime
via a debounced button (tap/double-tap/hold). BSD 2-Clause license.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

arduino/cosplay_lights/lightshow_format.h

@@ -0,0 +1,45 @@
+/*
+ * lightshow_format.h — Core data structures for show playback.
+ *
+ * All show data lives in PROGMEM (flash memory) to preserve the
+ * Arduino Uno's 2KB of RAM. The read_* helpers copy values out of
+ * PROGMEM so the rest of the code can work with them normally.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+#include <avr/pgmspace.h>
+#include <stdint.h>
+
+// One step in a lightshow: a target color and the time to reach it.
+struct Step {
+    uint8_t  r, g, b;        // Target RGB color (0–255 each)
+    uint16_t duration_ms;    // Milliseconds to fade from the previous color (0 = instant)
+};
+
+// Descriptor for one complete show: a pointer to its PROGMEM Step array and its length.
+struct ShowDef {
+    const Step* steps;    // Pointer to a PROGMEM Step array
+    uint16_t    length;   // Number of steps in the array
+};
+
+// Read one Step from PROGMEM into a regular struct.
+// Direct pointer access does not work for PROGMEM on AVR — use this helper.
+inline Step read_step(const Step* ptr) {
+    Step s;
+    s.r           = pgm_read_byte(&ptr->r);
+    s.g           = pgm_read_byte(&ptr->g);
+    s.b           = pgm_read_byte(&ptr->b);
+    s.duration_ms = pgm_read_word(&ptr->duration_ms);
+    return s;
+}
+
+// Read one ShowDef from a PROGMEM ShowDef array.
+// On AVR, pointers are 2 bytes wide, so pgm_read_word works for both fields.
+inline ShowDef read_show_def(const ShowDef* ptr) {
+    ShowDef sd;
+    sd.steps  = (const Step*)pgm_read_word(&ptr->steps);
+    sd.length = pgm_read_word(&ptr->length);
+    return sd;
+}