refactor: split display driver into panel + touch controller files

src/display/ now contains:
- DisplayDriver.h      — dispatcher + composed driver struct
- ILI9341_320x240.h    — ILI9341 TFT panel (320x240, SPI)
- XPT2046.h            — XPT2046 resistive touch controller

DisplayDriver inherits from both via multiple inheritance (zero-cost
at compile time). Files named after controller + resolution for clarity.
Future: HD44780_16x2.h for alphanumeric display.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: angeloINTJ

src/display/DisplayDriver.h

@@ -1,23 +1,25 @@
 /**
  * @file display/DisplayDriver.h
- * @brief Display driver dispatcher — selects the active display hardware at compile time.
- * @details Include this header to get the correct DisplayDriver implementation.
- * The active driver is selected via build flags in platformio.ini:
- *   SIMUT_DISPLAY_TFT   — ILI9341 320x240 TFT + XPT2046 touch (default)
- *   SIMUT_DISPLAY_ALPHA — 16x2 alphanumeric HD44780 (future)
+ * @brief Display driver — composes display panel + touch controller.
+ * @details The active hardware is selected at compile time via build flags.
+ * Currently supported:
+ *   Default: ILI9341 320x240 TFT + XPT2046 touch
+ *   Future:  HD44780 16x2 alphanumeric (SIMUT_DISPLAY_ALPHA)
  *
  * @project SIMUT — Integrated Universal Monitoring and Telemetry System
  * @license MIT License
  */
 
 #pragma once
 
-/* ── Driver selection ───────────────────────────────────────────────── */
-
 #if defined(SIMUT_DISPLAY_ALPHA)
-  // Future: #include "AlphaDisplayDriver.h"
+  // Future: #include "HD44780_16x2.h"
   #error "SIMUT_DISPLAY_ALPHA not yet implemented"
 #else
-  /* Default: ILI9341 TFT */
-  #include "TftDisplayDriver.h"
+  /* Default: ILI9341 TFT + XPT2046 touch */
+  #include "ILI9341_320x240.h"
+  #include "XPT2046.h"
+
+  struct DisplayDriver : public Ili9341_320x240, public Xpt2046_Touch {
+  };
 #endif

src/display/ILI9341_320x240.h

@@ -0,0 +1,27 @@
+/**
+ * @file display/ILI9341_320x240.h
+ * @brief ILI9341 TFT display driver — 320x240 pixels, SPI interface.
+ * @details Wraps TftWithOffset (Adafruit_ILI9341 with alignment offset).
+ * Provides GFX drawing surface, off-screen canvas, and screen dimensions.
+ *
+ * @project SIMUT — Integrated Universal Monitoring and Telemetry System
+ * @license MIT License
+ */
+#pragma once
+#include <Arduino.h>
+#include <Adafruit_GFX.h>
+#include <Adafruit_ILI9341.h>
+#include "TftWithOffset.h"
+
+struct Ili9341_320x240 {
+	TftWithOffset* tft   = nullptr;
+	GFXcanvas16*   canvas = nullptr;
+	GFXcanvas16*   canvasSmall = nullptr;
+	bool           firstInit = true;
+
+	int16_t width  = 320;
+	int16_t height = 240;
+
+	/* Delegate GFX drawing calls to TFT */
+	Adafruit_GFX* gfx( ) { return tft; }
+};

src/display/TftDisplayDriver.h

@@ -0,0 +1,16 @@
+/**
+ * @file display/XPT2046.h
+ * @brief XPT2046 resistive touch controller driver.
+ * @details Wraps the XPT2046_Touchscreen library. Provides touch point
+ * reading and raw touch state detection.
+ *
+ * @project SIMUT — Integrated Universal Monitoring and Telemetry System
+ * @license MIT License
+ */
+#pragma once
+#include <Arduino.h>
+#include <XPT2046_Touchscreen.h>
+
+struct Xpt2046_Touch {
+	XPT2046_Touchscreen* ts = nullptr;
+};