Add directory picking to home screen

src/screens/FileSelectionScreen.h

@@ -10,6 +10,7 @@
 
 class FileSelectionScreen final : public Screen {
   TaskHandle_t displayTaskHandle = nullptr;
+  std::string basepath = "/";
   std::vector<std::string> files;
   int selectorIndex = 0;
   bool updateRequired = false;
@@ -18,8 +19,9 @@ class FileSelectionScreen final : public Screen {
   static void taskTrampoline(void* param);
   [[noreturn]] void displayTaskLoop();
   void render() const;
+  void loadFiles();
 
- public:
+public:
   explicit FileSelectionScreen(EpdRenderer* renderer, const std::function<void(const std::string&)>& onSelect)
       : Screen(renderer), onSelect(onSelect) {}
   void onEnter() override;