fix: use RAII render lock everywhere (#916)

Follow-up to
https://github.com/crosspoint-reader/crosspoint-reader/pull/774

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<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

* **Refactor**
* Modernized internal synchronization mechanisms across multiple
components to improve code reliability and maintainability. All
functionality remains unchanged.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

src/activities/settings/OtaUpdateActivity.cpp

@@ -20,33 +20,37 @@ void OtaUpdateActivity::onWifiSelectionComplete(const bool success) {
 
   LOG_DBG("OTA", "WiFi connected, checking for update");
 
-  xSemaphoreTake(renderingMutex, portMAX_DELAY);
-  state = CHECKING_FOR_UPDATE;
-  xSemaphoreGive(renderingMutex);
+  {
+    RenderLock lock(*this);
+    state = CHECKING_FOR_UPDATE;
+  }
   requestUpdateAndWait();
 
   const auto res = updater.checkForUpdate();
   if (res != OtaUpdater::OK) {
     LOG_DBG("OTA", "Update check failed: %d", res);
-    xSemaphoreTake(renderingMutex, portMAX_DELAY);
-    state = FAILED;
-    xSemaphoreGive(renderingMutex);
+    {
+      RenderLock lock(*this);
+      state = FAILED;
+    }
     requestUpdate();
     return;
   }
 
   if (!updater.isUpdateNewer()) {
     LOG_DBG("OTA", "No new update available");
-    xSemaphoreTake(renderingMutex, portMAX_DELAY);
-    state = NO_UPDATE;
-    xSemaphoreGive(renderingMutex);
+    {
+      RenderLock lock(*this);
+      state = NO_UPDATE;
+    }
     requestUpdate();
     return;
   }
 
-  xSemaphoreTake(renderingMutex, portMAX_DELAY);
-  state = WAITING_CONFIRMATION;
-  xSemaphoreGive(renderingMutex);
+  {
+    RenderLock lock(*this);
+    state = WAITING_CONFIRMATION;
+  }
   requestUpdate();
 }