feat(sim): web viewer at /sim + touch injection at /api/sim/touch

- GET /sim: live viewer page, 2s screenshot refresh, click-to-touch
- POST /api/sim/touch?x,y,down: injects into sdl-pointer backend,
  auto-releases after 1.5s; simulator-only (404 on ESP32)
- sdl_input: file-scope touch override state with extern C setters

Devices/simulator/Source/drivers/sdl_input.h

@@ -42,6 +42,16 @@ bool sdl_input_pop_key(uint32_t* out_key);
  */
 bool sdl_input_has_queued_key(void);
 
+/**
+ * @brief Web-injected touch override (for headless sim viewer without SDL window).
+ * When active, sdl_pointer_get_touched_points() reports this state instead of
+ * the SDL mouse state. Coordinates are in LVGL logical pixels (e.g. 640x480).
+ * Pass pressed=false to release. Auto-releases after SIM_TOUCH_HOLD_MS unless
+ * refreshed (tap = press, wait, release handled by the web viewer).
+ */
+void sdl_input_set_touch_override(int32_t x, int32_t y, bool pressed);
+void sdl_input_clear_touch_override(void);
+
 #ifdef __cplusplus
 }
 #endif