- Add ScreensaverType::McpScreen to DisplaySettings enum, toString/fromString
- Add 'MCP Screen' option to the Display settings screensaver dropdown
- New McpScreensaver (Screensaver subclass): creates full-screen lv_canvas on
the overlay, allocates framebuffer in SPIRAM, registers canvas pointer in
McpSystemState, shows 'Waiting for LLM...' until first draw command arrives
- Wire McpScreensaver into DisplayIdle::activateScreensaver() switch
- McpSystem::ensureOverrideScreen() now calls displayidle::findService()->
startScreensaver() instead of launching McpOverrideApp — canvas appears
automatically on any LLM draw command
- Remove McpOverrideApp (replaced by screensaver), deregister from Tactility.cpp
- Remove mcpOverrideEnabled from McpSettings — no longer needed
- Simplify McpSettingsApp: remove Screen Override toggle, update info text to
direct users to Settings -> Display -> Screensaver -> MCP Screen
Adolfo Reyna