Add shared JC3636W518 board library and PlatformIO config

- shared/lib/JC3636W518: display/touch/backlight init with LVGL 9 glue
  (from scr_st77916.h), pin map, perf monitor (FPS/refresh/CPU)
- shared/include/lv_conf.h: LVGL 9.6 config for all projects
- shared/jc3636w518.ini: common platform/board/build settings
- display_gif_embedded uses it (23.2 fps, 86% CPU)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

shared/jc3636w518.ini

@@ -0,0 +1,43 @@
+; Shared PlatformIO settings for all JC3636W518 projects
+; (ESP32-S3R8, 16 MB QIO flash, 8 MB OPI PSRAM, 360x360 ST77916 QSPI + CST816S).
+;
+; Use from a project's platformio.ini:
+;   [platformio]
+;   extra_configs = <path to shared>/jc3636w518.ini
+;   [shared]
+;   dir = <path to shared>
+;   [env:jc3636w518]
+;   extends = jc3636w518
+
+[jc3636w518]
+; pioarduino = Arduino core 3.0.5 (ESP32_Display_Panel 0.1.4 needs core 3.x)
+platform = https://github.com/pioarduino/platform-espressif32/releases/download/51.03.05/platform-espressif32.zip
+board = esp32-s3-devkitc-1
+framework = arduino
+
+board_build.arduino.memory_type = qio_opi
+board_build.flash_mode = qio
+board_upload.flash_size = 16MB
+board_build.partitions = huge_app.csv
+
+; optimise for speed instead of size
+build_unflags = -Os
+build_flags =
+    -O2
+    -DBOARD_HAS_PSRAM
+    -DARDUINO_USB_CDC_ON_BOOT=1
+    ; LVGL (also when compiled as a library) uses shared/include/lv_conf.h
+    -DLV_CONF_INCLUDE_SIMPLE
+    -I${shared.dir}/include
+
+; shared/lib: JC3636W518 board library
+; vendor folder: ESP32_Display_Panel 0.1.4, ESP32_IO_Expander 0.0.2 (its lvgl 8.3.11 is not used)
+lib_extra_dirs =
+    ${shared.dir}/lib
+    ${shared.dir}/../2-Program Example/Demo_Arduino/library
+lib_deps = lvgl/lvgl@9.6.0
+
+upload_port = COM21
+monitor_port = COM21
+monitor_speed = 115200
+monitor_filters = esp32_exception_decoder