fix: ensure backlight turns back on during startMcpScreensaver and invalidate canvas on drawText

Tactility/Source/mcp/McpSystem.cpp

@@ -78,12 +78,12 @@ static bool display_ready(McpSystemState& state) {
 static bool ensureOverrideScreen() {
     auto& state = getState();
     if (state.drawArea == nullptr) {
-        // Activate the MCP Screen screensaver via DisplayIdle
+        // Activate the MCP screensaver via DisplayIdle (force McpScreensaver type)
         auto idleService = service::displayidle::findService();
         if (idleService) {
-            LOGGER.info("MCP draw triggered: starting MCP screensaver");
-            idleService->startScreensaver();
-            // Wait up to 500ms for the canvas to be registered
+            LOGGER.info("MCP draw triggered: activating MCP screensaver");
+            idleService->startMcpScreensaver();
+            // Wait up to 500ms for the canvas to be registered by McpScreensaver::start()
             for (int i = 0; i < 10; ++i) {
                 vTaskDelay(pdMS_TO_TICKS(50));
                 if (state.drawArea != nullptr) {
@@ -162,6 +162,7 @@ bool drawText(const std::string& text, int x, int y, int size) {
             }
 #endif
 
+            lv_obj_invalidate(state.drawArea);  // Trigger repaint
             state.overrideActive = true;
             success = true;
         }