fix(graphics): make on-screen keyboard lifecycle safe and RAII-managed (#11460)

- VirtualKeyboard::handleLongPress VK_ESC invoked the onTextEntered
  member std::function directly, but that callback path reaches
  OnScreenKeyboardModule::stop(), which destroys the keyboard - and
  with it the std::function whose invocation is still on the stack.
  handlePress and submitText already deliberately copy-and-clear before
  invoking for exactly this reason (CannedMessageModule documents the
  same hazard); do the same here.

- OnScreenKeyboardModule's keyboard becomes unique_ptr, replacing the
  delete-in-destructor / delete-then-new-in-start / delete-in-stop
  bookkeeping that runs on every keyboard open/close. The
  NotificationRenderer legacy hook receives a non-owning raw pointer,
  as before.

src/graphics/VirtualKeyboard.cpp

@@ -666,7 +666,13 @@ void VirtualKeyboard::handleLongPress()
         break;
     case VK_ESC:
         if (onTextEntered) {
-            onTextEntered("");
+            // Copy-and-clear before invoking, like handlePress/submitText: the callback can
+            // destroy this keyboard (OnScreenKeyboardModule::stop), so the member must not be
+            // the std::function still executing on the stack.
+            std::function<void(const std::string &)> callback = onTextEntered;
+            onTextEntered = nullptr;
+            inputText = "";
+            callback("");
         }
         break;
     default:

src/modules/OnScreenKeyboardModule.cpp

@@ -18,22 +18,12 @@ OnScreenKeyboardModule &OnScreenKeyboardModule::instance()
     return inst;
 }
 
-OnScreenKeyboardModule::~OnScreenKeyboardModule()
-{
-    if (keyboard) {
-        delete keyboard;
-        keyboard = nullptr;
-    }
-}
+OnScreenKeyboardModule::~OnScreenKeyboardModule() = default;
 
 void OnScreenKeyboardModule::start(const char *header, const char *initialText, uint32_t durationMs,
                                    std::function<void(const std::string &)> cb)
 {
-    if (keyboard) {
-        delete keyboard;
-        keyboard = nullptr;
-    }
-    keyboard = new VirtualKeyboard();
+    keyboard = std::make_unique<VirtualKeyboard>();
     callback = cb;
     if (header)
         keyboard->setHeader(header);
@@ -50,7 +40,7 @@ void OnScreenKeyboardModule::start(const char *header, const char *initialText,
     });
 
     // Maintain legacy compatibility hooks
-    NotificationRenderer::virtualKeyboard = keyboard;
+    NotificationRenderer::virtualKeyboard = keyboard.get();
     NotificationRenderer::textInputCallback = callback;
 }
 
@@ -58,10 +48,7 @@ void OnScreenKeyboardModule::stop(bool callEmptyCallback)
 {
     auto cb = callback;
     callback = nullptr;
-    if (keyboard) {
-        delete keyboard;
-        keyboard = nullptr;
-    }
+    keyboard.reset();
     // Keep NotificationRenderer legacy pointers in sync
     NotificationRenderer::virtualKeyboard = nullptr;
     NotificationRenderer::textInputCallback = nullptr;
@@ -74,7 +61,7 @@ void OnScreenKeyboardModule::handleInput(const InputEvent &event)
     if (!keyboard)
         return;
 
-    if (processVirtualKeyboardInput(event, keyboard))
+    if (processVirtualKeyboardInput(event, keyboard.get()))
         return;
 
     if (event.inputEvent == INPUT_BROKER_CANCEL)

src/modules/OnScreenKeyboardModule.h

@@ -7,6 +7,7 @@
 #include "graphics/VirtualKeyboard.h"
 #include <OLEDDisplay.h>
 #include <functional>
+#include <memory>
 #include <string>
 
 namespace graphics
@@ -34,7 +35,7 @@ class OnScreenKeyboardModule
     void onSubmit(const std::string &text);
     void onCancel();
 
-    VirtualKeyboard *keyboard = nullptr;
+    std::unique_ptr<VirtualKeyboard> keyboard;
     std::function<void(const std::string &)> callback;
 };