Improvements and fixes (#595)

- Fix BluetoothSettings app not updating when toggling on Bluetooth on
- Fix BluetoothSettings app crash when closing while scanning
- Fix BluetoothSettings app crash when turning BT off while scanning
- WebServer doesn't save config anymore as a side-effect of reading the config
- Add missing license headers
- Use TactilityKernel's time and delay functions instead of TactilityFreeRtos ones

Tactility/Private/Tactility/app/btmanage/BtManagePrivate.h

@@ -8,6 +8,9 @@
 #include <Tactility/bluetooth/Bluetooth.h>
 #include <tactility/drivers/bluetooth.h>
 
+#include <atomic>
+#include <memory>
+
 namespace tt::app::btmanage {
 
 class BtManage final : public App {
@@ -18,6 +21,15 @@ class BtManage final : public App {
     View view = View(&bindings, &state);
     bool isViewEnabled = false;
     Device* btDevice = nullptr;
+    bool callbackRegistered = false;
+
+    // Bumped by onHide() to invalidate any BT event already dispatched to the main
+    // task for this show/hide session (BtManage is reused across hide/show cycles -
+    // e.g. launching BtPeerSettings pushes it on top and hides this instance without
+    // destroying it). Kept in its own heap allocation, independent of BtManage's
+    // lifetime, so a dispatched callback can check it without touching a possibly
+    // already-destroyed `this`.
+    std::shared_ptr<std::atomic<int>> generation = std::make_shared<std::atomic<int>>(0);
 
 public:
 
@@ -35,6 +47,20 @@ public:
     State& getState() { return state; }
 
     void requestViewUpdate();
+
+    std::shared_ptr<std::atomic<int>> getGeneration() const { return generation; }
+
+    // Re-attempts registering the device event callback. Needed because the BLE driver
+    // only allocates its callback list while the device is started/on: a registration
+    // attempted while the radio is off silently no-ops, so this must be called again
+    // right after a successful bluetooth::start(). Idempotent: no-ops if already
+    // registered for this device, so it's safe to call from both onShow() and here.
+    void registerDeviceCallback(Device* dev);
+
+    // Call after bluetooth::stop(): the driver frees its callback list on stop, so the
+    // registration state must be cleared here too, without touching the (now-dangling)
+    // driver-side list.
+    void forgetCallbackRegistration();
 };
 
 } // namespace tt::app::btmanage