fix(graphics): crash and leak fixes across display drivers (#11455)

* fix(graphics): crash and leak fixes across display drivers

- TFTDisplay (portduino): _touch_instance was an uninitialized member,
  and the touch-config block only assigns it for xpt2046/stmpe610/
  ft5x06 while the guard accepts any configured module. A gt911 entry
  in config.yaml (supported by the color-UI path) reached
  _touch_instance->config() through an indeterminate pointer. Initialize
  to nullptr and guard the config block.

- Screen: the destructor freed normalFrames but leaked the owned
  dispdev (driver + framebuffer) and ui objects. Screen is genuinely
  destroyed on the portduino reboot path (screen = nullptr in
  Power.cpp).

- EInkDisplay2: GxEPD2_BW's constructor takes the low-level driver by
  value and stores a copy, so the 'new EINK_DISPLAY_MODEL' at nine
  sites was orphaned the moment connect() returned. Pass temporaries,
  as GxEPD2Multi already does.

- EInkParallelDisplay: the async full-refresh task cleared
  asyncFullRunning before nulling asyncTaskHandle, so the destructor
  could observe running==false with a stale handle and vTaskDelete a
  freed TCB. Null the handle first (same ordering fix the
  eink/Drivers/EInkParallel.cpp sibling already carries).

- Panel_sdl: initFrameBuffer only null-checked the first of its three
  allocations and returned true regardless, leaving the line array
  full of null+offset garbage on failure; later redraws would write
  through those. Check all three, release partial allocations, and
  return false.

* fix(graphics): propagate Panel_sdl framebuffer allocation failure from init()

Per review: initFrameBuffer() can now fail cleanly, so init() must not
register the monitor and report success when it does.

src/graphics/TFTDisplay.cpp

@@ -821,7 +821,7 @@ class LGFX : public lgfx::LGFX_Device
 {
     lgfx::Bus_SPI _bus_instance;
 
-    lgfx::ITouch *_touch_instance;
+    lgfx::ITouch *_touch_instance = nullptr;
 
   public:
     lgfx::Panel_Device *_panel_instance;
@@ -891,24 +891,28 @@ class LGFX : public lgfx::LGFX_Device
             } else if (portduino_config.touchscreenModule == ft5x06) {
                 _touch_instance = new lgfx::Touch_FT5x06;
             }
-            auto touch_cfg = _touch_instance->config();
+            // Not every module in the config enum has a branch above (gt911 is handled by the
+            // color-UI path in tftSetup.cpp), so the pointer can legitimately still be null here.
+            if (_touch_instance) {
+                auto touch_cfg = _touch_instance->config();
 
-            touch_cfg.pin_cs = portduino_config.touchscreenCS.pin;
-            touch_cfg.x_min = 0;
-            touch_cfg.x_max = portduino_config.displayHeight - 1;
-            touch_cfg.y_min = 0;
-            touch_cfg.y_max = portduino_config.displayWidth - 1;
-            touch_cfg.pin_int = portduino_config.touchscreenIRQ.pin;
-            touch_cfg.bus_shared = true;
-            touch_cfg.offset_rotation = portduino_config.touchscreenRotate;
-            if (portduino_config.touchscreenI2CAddr != -1) {
-                touch_cfg.i2c_addr = portduino_config.touchscreenI2CAddr;
-            } else {
-                touch_cfg.spi_host = portduino_config.touchscreen_spi_dev_int;
+                touch_cfg.pin_cs = portduino_config.touchscreenCS.pin;
+                touch_cfg.x_min = 0;
+                touch_cfg.x_max = portduino_config.displayHeight - 1;
+                touch_cfg.y_min = 0;
+                touch_cfg.y_max = portduino_config.displayWidth - 1;
+                touch_cfg.pin_int = portduino_config.touchscreenIRQ.pin;
+                touch_cfg.bus_shared = true;
+                touch_cfg.offset_rotation = portduino_config.touchscreenRotate;
+                if (portduino_config.touchscreenI2CAddr != -1) {
+                    touch_cfg.i2c_addr = portduino_config.touchscreenI2CAddr;
+                } else {
+                    touch_cfg.spi_host = portduino_config.touchscreen_spi_dev_int;
+                }
+
+                _touch_instance->config(touch_cfg);
+                _panel_instance->setTouch(_touch_instance);
             }
-
-            _touch_instance->config(touch_cfg);
-            _panel_instance->setTouch(_touch_instance);
         }
 #if defined(SDL_h_)
         if (portduino_config.displayPanel == x11) {