Screenshot app & service (#42)

- Added screenshot app & service (PC-only for now)
- Updated docs with screenshots and new device photo
- Add fake statusbar icons for PC/sim build
- added `lv_screenshot` library based on `lv_100ask_screenshot` from https://github.com/100askTeam/lv_lib_100ask
- T-Deck WiFi is now allocated into SPI RAM
- Created `tt_service_find()` to find services by their id

libs/lv_screenshot/CMakeLists.txt

@@ -0,0 +1,30 @@
+cmake_minimum_required(VERSION 3.16)
+
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CXX_EXTENSIONS OFF)
+
+file(GLOB SOURCES "src/*.c")
+file(GLOB HEADERS "src/*.h")
+
+add_library(lv_screenshot STATIC)
+
+target_sources(lv_screenshot
+    PRIVATE ${SOURCES}
+    PUBLIC ${HEADERS}
+)
+
+target_include_directories(lv_screenshot
+    PRIVATE private
+    PUBLIC src
+)
+
+if (DEFINED ENV{ESP_IDF_VERSION})
+    target_link_libraries(lv_screenshot
+        PUBLIC idf::lvgl
+    )
+else()
+    target_link_libraries(lv_screenshot
+        PUBLIC lvgl
+    )
+endif()