Merge develop into main (#327)

## New features
- Implemented support for app packaging in firmware and `tactility.py`: load `.app` files instead of `.elf` files. Install apps remotely or via `FileBrowser`.
- Ensure headless mode works: all services that require LVGL can deal with the absence of a display
- Service `onStart()` is now allowed to fail (return `bool` result)
- Added and improved various file-related helper functions

## Improvements
- Completely revamped the SystemInfo app UI
- Improved Calculator UI of internal and external variant
- Fix Chat UI and removed the emoji buttons for now
- Fix for toolbar bottom padding issue in all apps

## Fixes
- Fix for allowing recursive locking for certain SPI SD cards
& more

Tactility/Source/service/statusbar/Statusbar.cpp

@@ -249,7 +249,12 @@ public:
         lvgl::statusbar_icon_remove(gps_icon_id);
     }
 
-    void onStart(ServiceContext& serviceContext) override {
+    bool onStart(ServiceContext& serviceContext) override {
+        if (lv_screen_active() == nullptr) {
+            TT_LOG_E(TAG, "No display found");
+            return false;
+        }
+
         paths = serviceContext.getPaths();
 
         // TODO: Make thread-safe for LVGL
@@ -265,6 +270,8 @@ public:
 
         // We want to try and scan more often in case of startup or scan lock failure
         updateTimer->start(1000);
+
+        return true;
     }
 
     void onStop(ServiceContext& service) override{