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

Tactility/Source/PartitionsPosix.cpp

@@ -0,0 +1,103 @@
+#ifndef ESP_PLATFORM
+
+#include <Tactility/PartitionsPosix.h>
+#include <Tactility/MountPoints.h>
+
+#include <tactility/error.h>
+#include <tactility/filesystem/file_system.h>
+#include <tactility/log.h>
+
+#include <cerrno>
+#include <climits>
+#include <cstdlib>
+#include <cstring>
+
+namespace tt {
+
+constexpr auto* TAG = "Partitions";
+
+// region file_system stub
+
+// A plain host directory has no real mount/unmount step to perform - "mounted" here just tracks
+// whether file_system_remove()'s precondition (must be unmounted first) has been satisfied.
+struct DirectoryFsData {
+    char path[PATH_MAX];
+    bool mounted;
+};
+
+static DirectoryFsData system_fs_data;
+static DirectoryFsData data_fs_data;
+static FileSystem* system_fs = nullptr;
+static FileSystem* data_fs = nullptr;
+
+static error_t mount(void* data) {
+    static_cast<DirectoryFsData*>(data)->mounted = true;
+    return ERROR_NONE;
+}
+
+static error_t unmount(void* data) {
+    static_cast<DirectoryFsData*>(data)->mounted = false;
+    return ERROR_NONE;
+}
+
+static bool is_mounted(void* data) {
+    return static_cast<DirectoryFsData*>(data)->mounted;
+}
+
+static error_t get_path(void* data, char* out_path, size_t out_path_size) {
+    auto* fs_data = static_cast<DirectoryFsData*>(data);
+    if (strlen(fs_data->path) >= out_path_size) {
+        return ERROR_BUFFER_OVERFLOW;
+    }
+    strcpy(out_path, fs_data->path);
+    return ERROR_NONE;
+}
+
+static const FileSystemApi directory_fs_api = {
+    .mount = mount,
+    .unmount = unmount,
+    .is_mounted = is_mounted,
+    .get_path = get_path,
+};
+
+// endregion file_system stub
+
+// relative_path is resolved against the process' current working directory (the simulator is
+// expected to run with Data/ as its working directory, so file::SYSTEM_PARTITION_NAME/
+// DATA_PARTITION_NAME here match file::MOUNT_POINT_SYSTEM/MOUNT_POINT_DATA).
+static FileSystem* registerDirectoryFs(const char* relativePath, DirectoryFsData* outData) {
+    if (realpath(relativePath, outData->path) == nullptr) {
+        LOG_E(TAG, "Failed to resolve '%s' to an absolute path: %s", relativePath, strerror(errno));
+        return nullptr;
+    }
+    outData->mounted = true;
+    return file_system_add(&directory_fs_api, outData);
+}
+
+static void unregisterDirectoryFs(FileSystem* fs) {
+    if (fs == nullptr) {
+        return;
+    }
+    file_system_unmount(fs);
+    file_system_remove(fs);
+}
+
+bool initPartitionsPosix() {
+    system_fs = registerDirectoryFs(file::SYSTEM_PARTITION_NAME, &system_fs_data);
+    if (system_fs == nullptr) {
+        return false;
+    }
+
+    data_fs = registerDirectoryFs(file::DATA_PARTITION_NAME, &data_fs_data);
+    if (data_fs == nullptr) {
+        unregisterDirectoryFs(system_fs);
+        system_fs = nullptr;
+        return false;
+    }
+
+    return true;
+}
+
+} // namespace
+
+#endif // ESP_PLATFORM