Implement posix app loading (#643)

- Added POSIX desktop support for SDK builds, application packaging, and integration testing.
- Added POSIX filesystem partitions and improved application path handling.
- Added simulator support for loading and running applications dynamically.
- Improved simulator task stack handling and display startup reliability.
- Improved simulator display scaling, resizing, high-DPI support, and pointer accuracy.
- Fixed LVGL timers and input polling on POSIX. (fixes simulator with Linux on some Intel graphics platforms)
- Standardized data paths across platforms.
- Logging now works via separate task: this allows apps to write to log without it affecting their stdout (for apps that output text as relevant date for other apps, like the File Selection app)
- Fixes for app stdio

Devices/simulator/Source/drivers/sdl_display.h

@@ -1,6 +1,8 @@
 // SPDX-License-Identifier: Apache-2.0
 #pragma once
 
+#include <SDL2/SDL.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -12,6 +14,22 @@ struct SdlDisplayConfig {
     uint16_t vertical_resolution;
 };
 
+/**
+ * @return the display's renderer, or NULL if the display hasn't drawn its first frame yet
+ *     (see sdl_display_lazy_init() in sdl_display.cpp). Used by sdl_input.cpp to map window
+ *     coordinates back to the fixed logical resolution the renderer scales to fit the window.
+ */
+SDL_Renderer* sdl_display_get_renderer(void);
+
+/**
+ * @brief Re-presents the already-drawn frame at the renderer's current scale. Call this when the
+ *     window is resized: the window size change alone doesn't make SDL re-blit the last frame at
+ *     the new scale until something calls SDL_RenderPresent() again, and LVGL won't do that on
+ *     its own since nothing it's tracking actually changed. No-op if the display hasn't drawn its
+ *     first frame yet.
+ */
+void sdl_display_present_now(void);
+
 #ifdef __cplusplus
 }
 #endif