feat: add board configuration system, refactor Config.h

Board selection driven by -DTARGET_E32R35T or -DTARGET_WAVESHARE_S3_43.
Defaults to E32R35T for backward compatibility.

All hardware pin definitions moved from Config.h to board headers.
SCREEN_WIDTH/SCREEN_HEIGHT now come from board headers.
Config.h is now purely application-level configuration.

New files:
  BoardConfig.h              — board selector
  boards/board_e32r35t.h     — E32R35T pins, display, touch config
  boards/board_waveshare_s3.h — Waveshare S3 4.3" pins, display, touch config

Modified:
  Config.h — removed hardware pins section, added #include BoardConfig.h,
             added HOLD_DURATION_MS to timing section

sketches/doorbell-touch-esp32-32e/BoardConfig.h

@@ -0,0 +1,18 @@
+#pragma once
+// ═══════════════════════════════════════════════════════════════════
+// Board selector — driven by build flags
+// Pass -DTARGET_E32R35T or -DTARGET_WAVESHARE_S3_43
+// ═══════════════════════════════════════════════════════════════════
+
+#if defined(TARGET_E32R35T)
+  #include "boards/board_e32r35t.h"
+
+#elif defined(TARGET_WAVESHARE_S3_43)
+  #include "boards/board_waveshare_s3.h"
+
+#else
+  // Default to E32R35T for backward compatibility with existing builds
+  #pragma message("No TARGET_* defined — defaulting to E32R35T")
+  #define TARGET_E32R35T
+  #include "boards/board_e32r35t.h"
+#endif

sketches/doorbell-touch-esp32-32e/Config.h

@@ -1,5 +1,7 @@
 #pragma once
 
+#include "BoardConfig.h"
+
 // =====================================================================
 //  Debug
 // =====================================================================
@@ -42,6 +44,7 @@ static const int NUM_WIFI = sizeof(wifiNetworks) / sizeof(wifiNetworks[0]);
 #define NTP_SYNC_INTERVAL_MS   3600000
 #define WAKE_DISPLAY_MS        5000
 #define TOUCH_DEBOUNCE_MS      300
+#define HOLD_DURATION_MS       2000
 #define HEARTBEAT_INTERVAL_MS  30000
 
 #if DEBUG_MODE
@@ -51,41 +54,6 @@ static const int NUM_WIFI = sizeof(wifiNetworks) / sizeof(wifiNetworks[0]);
 #endif
 
 // =====================================================================
-//  E32R35T Hardware Pins (hardwired on PCB — do not change)
+//  Hardware pins are now in boards/board_*.h via BoardConfig.h
+//  Screen dimensions (SCREEN_WIDTH, SCREEN_HEIGHT) also come from there.
 // =====================================================================
-// LCD (HSPI)
-#define PIN_LCD_CS    15
-#define PIN_LCD_DC     2
-#define PIN_LCD_MOSI  13
-#define PIN_LCD_SCLK  14
-#define PIN_LCD_MISO  12
-#define PIN_LCD_BL    27
-
-// Touch (XPT2046, shares HSPI)
-#define PIN_TOUCH_CS  33
-#define PIN_TOUCH_IRQ 36
-
-// SD Card (VSPI — for future use)
-#define PIN_SD_CS     5
-#define PIN_SD_MOSI   23
-#define PIN_SD_SCLK   18
-#define PIN_SD_MISO   19
-
-// RGB LED (active low)
-#define PIN_LED_RED   22
-#define PIN_LED_GREEN 16
-#define PIN_LED_BLUE  17
-
-// Audio
-#define PIN_AUDIO_EN   4
-#define PIN_AUDIO_DAC 26
-
-// Battery ADC
-#define PIN_BAT_ADC   34
-
-// =====================================================================
-//  Display
-// =====================================================================
-#define SCREEN_WIDTH   480   // landscape
-#define SCREEN_HEIGHT  320
-

sketches/doorbell-touch-esp32-32e/boards/board_e32r35t.h

@@ -0,0 +1,50 @@
+#pragma once
+// ═══════════════════════════════════════════════════════════════════
+// Board: E32R35T — ESP32-WROOM-32E + 3.5" ST7796S SPI + XPT2046
+// ═══════════════════════════════════════════════════════════════════
+
+#define BOARD_NAME            "E32R35T"
+
+// ── Display ─────────────────────────────────────────────────────
+#define SCREEN_WIDTH          480
+#define SCREEN_HEIGHT         320
+#define DISPLAY_ROTATION      1
+
+// ── Driver selection ────────────────────────────────────────────
+#define USE_TFT_ESPI          1
+#define USE_ARDUINO_GFX       0
+#define USE_TOUCH_XPT2046     1
+#define USE_TOUCH_GT911       0
+
+// ── Hardware capabilities ───────────────────────────────────────
+#define HAS_PSRAM             0
+
+// ── LCD (HSPI) ──────────────────────────────────────────────────
+#define PIN_LCD_CS    15
+#define PIN_LCD_DC     2
+#define PIN_LCD_MOSI  13
+#define PIN_LCD_SCLK  14
+#define PIN_LCD_MISO  12
+#define PIN_LCD_BL    27
+
+// ── Touch (XPT2046, shares HSPI) ───────────────────────────────
+#define PIN_TOUCH_CS  33
+#define PIN_TOUCH_IRQ 36
+
+// ── SD Card (VSPI — for future use) ────────────────────────────
+#define PIN_SD_CS     5
+#define PIN_SD_MOSI   23
+#define PIN_SD_SCLK   18
+#define PIN_SD_MISO   19
+
+// ── RGB LED (active low) ───────────────────────────────────────
+#define PIN_LED_RED   22
+#define PIN_LED_GREEN 16
+#define PIN_LED_BLUE  17
+
+// ── Audio ───────────────────────────────────────────────────────
+#define PIN_AUDIO_EN   4
+#define PIN_AUDIO_DAC 26
+
+// ── Battery ADC ─────────────────────────────────────────────────
+#define PIN_BAT_ADC   34

sketches/doorbell-touch-esp32-32e/boards/board_waveshare_s3.h

@@ -0,0 +1,73 @@
+#pragma once
+// ═══════════════════════════════════════════════════════════════════
+// Board: Waveshare ESP32-S3 Touch LCD 4.3"
+// 800x480 RGB parallel + GT911 capacitive touch
+//
+// NOTE: Pin assignments are typical for this board revision.
+// Verify against your specific board's schematic.
+// The Arduino board variant 'waveshare_esp32_s3_touch_lcd_43'
+// may override some of these via its pins_arduino.h.
+// ═══════════════════════════════════════════════════════════════════
+
+#define BOARD_NAME            "WS_S3_43"
+
+// ── Display ─────────────────────────────────────────────────────
+#define SCREEN_WIDTH          800
+#define SCREEN_HEIGHT         480
+#define DISPLAY_ROTATION      0   // native landscape
+
+// ── Driver selection ────────────────────────────────────────────
+#define USE_TFT_ESPI          0
+#define USE_ARDUINO_GFX       1
+#define USE_TOUCH_XPT2046     0
+#define USE_TOUCH_GT911       1
+
+// ── Hardware capabilities ───────────────────────────────────────
+#define HAS_PSRAM             1
+
+// ── Backlight ───────────────────────────────────────────────────
+#define PIN_LCD_BL            2
+
+// ── GT911 I2C touch controller ──────────────────────────────────
+#define TOUCH_SDA             8
+#define TOUCH_SCL             9
+#define TOUCH_INT             4
+#define TOUCH_RST             5
+
+// ── RGB LCD data pins (ESP32-S3 LCD_CAM peripheral) ─────────────
+// Adjust if your board revision differs
+#define LCD_DE      40
+#define LCD_VSYNC   41
+#define LCD_HSYNC   39
+#define LCD_PCLK    42
+#define LCD_R0      45
+#define LCD_R1      48
+#define LCD_R2      47
+#define LCD_R3      21
+#define LCD_R4      14
+#define LCD_G0       5
+#define LCD_G1       6
+#define LCD_G2       7
+#define LCD_G3      15
+#define LCD_G4      16
+#define LCD_G5       4
+#define LCD_B0       8
+#define LCD_B1       3
+#define LCD_B2      46
+#define LCD_B3       9
+#define LCD_B4       1
+
+// ── Peripherals not present on this board ───────────────────────
+// These are left undefined intentionally. Code that uses them
+// should guard with #ifdef PIN_LED_RED etc.
+// Uncomment and set values if your carrier board adds them.
+//
+// #define PIN_LED_RED   -1
+// #define PIN_LED_GREEN -1
+// #define PIN_LED_BLUE  -1
+// #define PIN_AUDIO_EN  -1
+// #define PIN_AUDIO_DAC -1
+// #define PIN_BAT_ADC   -1
+// #define PIN_SD_CS     -1
+// #define PIN_TOUCH_CS  -1
+// #define PIN_TOUCH_IRQ -1