fix(displayidle): avoid LVGL->MCP lock inversion that could freeze RLCD

Read MCP override state outside LVGL lock in tick().
Previously: LVGL lock -> MCP mutex (tick) vs MCP mutex -> LVGL lock (video task startMcpScreensaver) = deadlock risk observed on RLCD when text tool called.
Now: MCP state read first, then LVGL lock. Preserves <1s flash guard (isMcpActive).

Board: waveshare-esp32-s3-rlcd 0x2b78b0 32%% free, flashed to /dev/cu.usbmodem101

Co-Authored-By: internal-model

Tactility/Source/service/displayidle/DisplayIdle.cpp

@@ -147,6 +147,16 @@ void DisplayIdleService::updateScreensaver() {
 }
 
 void DisplayIdleService::tick() {
+    // Check if MCP override is active — must not be auto-stopped by idle logic
+    // READ OUTSIDE LVGL lock to avoid lock inversion:
+    // MCP video task locks mutex -> LVGL, we must NOT do LVGL -> mutex
+    bool isMcpActive = false;
+    {
+        auto& st = mcp::getState();
+        std::lock_guard<std::mutex> lk(st.mutex);
+        isMcpActive = (st.drawArea != nullptr) || st.overrideActive;
+    }
+
     if (!lvgl::lock(100)) {
         return;
     }
@@ -163,14 +173,6 @@ void DisplayIdleService::tick() {
     uint32_t inactive_ms = 0;
     inactive_ms = lv_display_get_inactive_time(nullptr);
 
-    // Check if MCP override is active — it must not be auto-stopped by idle logic
-    bool isMcpActive = false;
-    {
-        auto& st = mcp::getState();
-        std::lock_guard<std::mutex> lk(st.mutex);
-        isMcpActive = (st.drawArea != nullptr) || st.overrideActive;
-    }
-
     // Only update if not stopping (prevents lag on touch) — skip for MCP (no animation)
     if (displayDimmed && screensaverOverlay && !stopScreensaverRequested.load(std::memory_order_acquire) && !isMcpActive) {
         // Check if screensaver should auto-off after 5 minutes