feat(mcp): restore MCP system with native log.h

- MCP 3.3K LOC: McpSystem 1899 + McpHandler 1029 + McpScreensaver + 2 apps
- Uses native tactility/log.h TAG macros, no old Logger.h
- DisplaySettings McpScreen enum, WebServer coexistence (MCP enabled starts HTTP)
- DisplayIdle: startMcpScreensaver + isDeviceCharging + lock inversion fix 3629ffef
- LVGL 512K PSRAM cache retained from previous perf patch
- Audio kept upstream es8311-module per note we might not need custom

Tactility/Source/settings/DisplaySettings.cpp

@@ -63,6 +63,8 @@ static std::string toString(ScreensaverType type) {
         case Mystify: return "Mystify";
         case MatrixRain: return "MatrixRain";
         case StackChan: return "StackChan";
+        case McpScreen: return "McpScreen";
+        case Count: return "None";
         default: std::unreachable();
     }
 }
@@ -73,6 +75,7 @@ static bool fromString(const std::string& str, ScreensaverType& type) {
     else if (str == "Mystify") { type = ScreensaverType::Mystify; return true; }
     else if (str == "MatrixRain") { type = ScreensaverType::MatrixRain; return true; }
     else if (str == "StackChan") { type = ScreensaverType::StackChan; return true; }
+    else if (str == "McpScreen") { type = ScreensaverType::McpScreen; return true; }
     else { return false; }
 }