Add LCD1602A I2C test with SoftSPI touch and LVGL.

PCF8574 backpack on SDA=GPIO22/SCL=GPIO27, demo/hello/clear/backlight UI, and flashable firmware/cyd package.

Co-authored-by: Cursor <cursoragent@cursor.com>

include/lcd.h

@@ -0,0 +1,20 @@
+#pragma once
+
+#include <stddef.h>
+#include <stdint.h>
+
+void lcd_init();
+
+bool lcd_ok();
+uint8_t lcd_addr();
+
+void lcd_set_backlight(bool on);
+bool lcd_backlight();
+
+void lcd_clear();
+void lcd_set_line(uint8_t row, const char *text);
+void lcd_get_line(uint8_t row, char *out, size_t out_len);
+
+/** 写入两行示例文案并点亮背光 */
+void lcd_demo(uint8_t index);
+uint8_t lcd_demo_count();

include/pins.h

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+#pragma once
+
+// CYD ESP32-2432S028R — 触控/屏脚与 tftest 一致
+// LCD1602A + I2C 转接板（PCF8574）：SDA=GPIO22，SCL=GPIO27
+// 常见地址 0x27 / 0x3F（上电扫描）
+
+#define TFT_BL_PIN 21
+
+#define CYD_TOUCH_IRQ  36
+#define CYD_TOUCH_MOSI 32
+#define CYD_TOUCH_MISO 39
+#define CYD_TOUCH_CLK  25
+#define CYD_TOUCH_CS   33
+
+#define LCD_I2C_SDA_PIN 22
+#define LCD_I2C_SCL_PIN 27
+#define LCD_I2C_FREQ_HZ 100000
+#define LCD_COLS 16
+#define LCD_ROWS 2
+
+#define SCREEN_WIDTH  240
+#define SCREEN_HEIGHT 320
+#define UI_HOR_RES    320
+#define UI_VER_RES    240

include/touch.h

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+#pragma once
+
+#include <lvgl.h>
+#include <stdint.h>
+
+void touch_init();
+void touch_read_cb(lv_indev_t *indev, lv_indev_data_t *data);
+
+// 调试：最近一次触点（物理 / LVGL 旋转后逻辑）
+extern int16_t g_dbg_phys_x, g_dbg_phys_y;
+extern int16_t g_dbg_logic_x, g_dbg_logic_y;
+extern bool g_dbg_touch_down;

include/ui.h

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+#pragma once
+
+void ui_create();
+void ui_refresh_lcd();