Project restructuring: add tactility-headless (#55)

- Created `tactility-headless` to support ESP32 firmwares that don't require graphics
- `tactility` subproject now contains both PC and ESP32 code (to avoid having to split up `tactility` and `tactility-headless` into separate projects, which would result in a very complex dependency tree)
- `tactility` subproject is now defined as component for ESP32 and as regular module for PC
- Improvements for dispatcher
- Added `project-structure.puml` to docs
- `Gui` service now depends on `Loader` service instead of the reverse
- Added `statusbar_updater` service for updating Wi-Fi and SD card icons

boards/yellow_board/CMakeLists.txt

@@ -1,7 +1,5 @@
 idf_component_register(
     SRC_DIRS "."
     INCLUDE_DIRS "."
-    REQUIRES esp_lvgl_port esp_lcd_touch_cst816s esp_lcd_ili9341 driver vfs fatfs
+    REQUIRES tactility esp_lvgl_port esp_lcd_touch_cst816s esp_lcd_ili9341 driver vfs fatfs
 )
-
-target_link_libraries(${COMPONENT_LIB} ${IDF_TARGET_NAME} tactility)

boards/yellow_board/yellow_board.c

@@ -11,6 +11,6 @@ const HardwareConfig yellow_board_24inch_cap = {
     .display = {
         .set_backlight_duty = &twodotfour_backlight_set
     },
-    .init_lvgl = &twodotfour_lvgl_init,
+    .init_graphics = &twodotfour_lvgl_init,
     .sdcard = &twodotfour_sdcard
 };