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/private/save_bmp.h

@@ -0,0 +1,14 @@
+#pragma once
+
+#include "lvgl.h"
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+bool lve_screenshot_save_bmp_file(const uint8_t* image, uint32_t w, uint32_t h, uint32_t bpp, const char* filename);
+
+#ifdef __cplusplus
+}
+#endif