mod: adapt mod activities to #774 render() pattern

Migrate 5 mod Activity subclasses from old polling-based
display task pattern to the upstream render() super-class
pattern with freeRTOS notification:

- EpubReaderBookmarkSelectionActivity
- DictionaryWordSelectActivity
- DictionarySuggestionsActivity
- DictionaryDefinitionActivity
- LookedUpWordsActivity

Changes: remove own TaskHandle/SemaphoreHandle/updateRequired,
use requestUpdate() + render(RenderLock&&) override, fix
potential deadlocks around enterNewActivity() calls.

Also fix stale conflict marker in EpubReaderMenuActivity.h.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/activities/reader/LookedUpWordsActivity.h

@@ -1,8 +1,4 @@
 #pragma once
-#include <freertos/FreeRTOS.h>
-#include <freertos/semphr.h>
-#include <freertos/task.h>
-
 #include <functional>
 #include <string>
 #include <vector>
@@ -25,6 +21,7 @@ class LookedUpWordsActivity final : public ActivityWithSubactivity {
   void onEnter() override;
   void onExit() override;
   void loop() override;
+  void render(Activity::RenderLock&&) override;
 
  private:
   std::string cachePath;
@@ -35,7 +32,6 @@ class LookedUpWordsActivity final : public ActivityWithSubactivity {
 
   std::vector<std::string> words;
   int selectedIndex = 0;
-  bool updateRequired = false;
   bool pendingBackFromDef = false;
   bool pendingExitToReader = false;
   ButtonNavigator buttonNavigator;
@@ -45,11 +41,5 @@ class LookedUpWordsActivity final : public ActivityWithSubactivity {
   bool ignoreNextConfirmRelease = false;
   int pendingDeleteIndex = 0;
 
-  TaskHandle_t displayTaskHandle = nullptr;
-  SemaphoreHandle_t renderingMutex = nullptr;
-
   int getPageItems() const;
-  void renderScreen();
-  static void taskTrampoline(void* param);
-  [[noreturn]] void displayTaskLoop();
 };