Revert backlight to active-high, implement Draw_Sunflower_Pattern boot screen for empty storage states

sound_picture_app/Display_PNG.cpp

@@ -122,3 +122,38 @@ void Draw_Candle_Flicker() {
   
   LCD_addWindow(71, 125, 101, 167, canvas);
 }
+
+void Draw_Sunflower_Pattern() {
+  clearScreen();
+  
+  // Fill the screen with a stylized sunflower:
+  // Center of screen is x=86, y=160.
+  uint16_t line[172];
+  
+  for (int y = 0; y < 320; y++) {
+    for (int x = 0; x < 172; x++) {
+      int dx = x - 86;
+      int dy = y - 160;
+      int dist2 = dx*dx + dy*dy;
+      
+      if (dist2 < 30*30) {
+        // Sunflower center (brown)
+        line[x] = 0x5140; // dark brown
+      } else if (dist2 < 65*65 && (abs(dx) < 15 || abs(dy) < 15 || abs(dx-dy) < 12 || abs(dx+dy) < 12)) {
+        // Golden petals
+        line[x] = 0xFDA0; // Golden orange/yellow
+      } else if (dist2 < 70*70 && (abs(dx) < 22 || abs(dy) < 22)) {
+        // Outer petals highlight
+        line[x] = 0xFFE0; // Yellow
+      } else {
+        // Charcoal background
+        line[x] = 0x18C3; // Very dark warm gray
+      }
+    }
+    // Swap bytes for ST7789 SPI big-endian transfer
+    for (int x = 0; x < 172; x++) {
+      line[x] = __builtin_bswap16(line[x]);
+    }
+    LCD_addWindow(0, y, 171, y, line);
+  }
+}