examples/lvgldemo: camera frame-callback architecture and style cleanup

- camera_module: restructure around a frame-callback contract
  (esp32p4_mipi_csi_frame_cb_t) with an explicit capture state machine
  (CSI_START -> STREAMING), current-frame snapshot for the LVGL timer,
  crop + nearest-neighbor scale into the preview canvas
- ui_main / boot_screen / audio_beep / lvgldemo: translate file-header
  and inline comments to English (NuttX style), move declarations to
  the canonical section order, keep the UI <-> audio decoupling via
  board_audio_beep()
- zh_font_16 / zh_font_40: regenerate with lv_font_conv (full CJK
  symbol set, no local build paths in headers)
- lvgldemo: parameterize boot flow (BOOT_DURATION_MS, status text)

Signed-off-by: IsXiaoXiaoZHou <zhou15325553865@outlook.com>

Author: IsXiaoXiaoZhou

examples/lvgldemo/audio_beep.c

@@ -1,11 +1,16 @@
 /****************************************************************************
  * apps/examples/lvgldemo/audio_beep.c
  *
- * 扬声器提示音播放。
+ * Speaker beep placeholder implementation.
  *
- * 说明：当前为占位实现（播放逻辑未接入），扬声器链路（ES8311 + I2S）
- * 在 openvela 侧完成后，替换此文件为真实播放实现。UI 通过
- * board_audio_beep() 触发提示音，二者解耦。
+ * The real playback path (ES8311 + I2S on the openvela side) is not
+ * wired yet; once it lands, replace the body of board_audio_beep()
+ * with an actual playback implementation. The UI only calls
+ * board_audio_beep(), so the two sides stay decoupled.
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
  ****************************************************************************/
 
 #include <nuttx/config.h>
@@ -27,12 +32,13 @@
  * Name: board_audio_beep
  *
  * Description:
- *   播放一句话/提示音。真实实现待接入 openvela 音频链路后补充。
+ *   Play a short beep / spoken prompt. The real implementation will be
+ *   added once the openvela audio path is ready.
  ****************************************************************************/
 
 void board_audio_beep(void)
 {
 #if defined(CONFIG_AUDIO) && defined(CONFIG_AUDIO_I2S)
-  /* 占位：后续实现通过 /dev/audio/pcm0 播放合成提示音。 */
+  /* Placeholder: play a synthesized beep via /dev/audio/pcm0 later. */
 #endif
-}
+}

examples/lvgldemo/boot_screen.c

@@ -1,27 +1,45 @@
 /****************************************************************************
  * apps/examples/lvgldemo/boot_screen.c
  *
- * 开机界面：白底 + 居中 openvela logo（RGB565 图像数据）+ 底部进度条。
- * 主循环通过 boot_screen_update() 推进进度与"正在启动"状态文字。
+ * Boot screen: white background, centered openvela logo (RGB565 data)
+ * and a progress bar at the bottom. The main loop calls
+ * boot_screen_update() to advance the progress and the status text.
  ****************************************************************************/
 
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <stdint.h>
+
 #include "boot_screen.h"
 #include "logo_data.h"
 
-#include <stdint.h>
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
 
-LV_FONT_DECLARE(zh_font_16);
+/* Light theme colors, consistent with the main screen */
 
-/* 与主界面一致的浅色主题配色 */
 #define C_PROGRESS_BG   lv_color_hex(0xe5e7eb)
 #define C_PROGRESS_BAR  lv_color_hex(0x3b82f6)
 #define C_STATUS_TEXT   lv_color_hex(0x6b7280)
 
 #define BOOT_BAR_W      420
 #define BOOT_BAR_H      8
-#define BOOT_BAR_Y      220   /* 相对屏幕中心的纵向偏移 */
+#define BOOT_BAR_Y      220  /* vertical offset from the screen center */
 #define BOOT_TEXT_Y     185
 
+/* Starting-up status text (Chinese, \u-escaped below) */
+
+#define BOOT_STATUS_TEXT "\u6b63\u5728\u542f\u52a8"
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+LV_FONT_DECLARE(zh_font_16);
+
 static lv_obj_t *s_progress = NULL;
 static lv_obj_t *s_status   = NULL;
 
@@ -39,40 +57,74 @@ static const lv_image_dsc_t boot_logo =
   .data = (const uint8_t *)logo_data,
 };
 
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: boot_screen_show
+ *
+ * Description:
+ *   Draw the boot screen (logo + progress bar + status label) on the
+ *   given screen object.
+ *
+ * Input Parameters:
+ *   scr - The LVGL screen object to draw onto.
+ *
+ ****************************************************************************/
+
 void boot_screen_show(lv_obj_t *scr)
 {
   lv_obj_t *img;
 
   lv_obj_set_style_bg_color(scr, lv_color_white(), 0);
   lv_obj_set_style_bg_opa(scr, LV_OPA_COVER, 0);
 
-  /* 居中 openvela logo，略向上留出底部进度区 */
+  /* Centered openvela logo, shifted up to leave room for the bar */
+
   img = lv_image_create(scr);
   lv_image_set_src(img, &boot_logo);
   lv_obj_align(img, LV_ALIGN_CENTER, 0, -40);
 
-  /* 底部进度条 */
+  /* Bottom progress bar */
+
   s_progress = lv_bar_create(scr);
   lv_obj_remove_style_all(s_progress);
   lv_obj_set_size(s_progress, BOOT_BAR_W, BOOT_BAR_H);
   lv_obj_align(s_progress, LV_ALIGN_CENTER, 0, BOOT_BAR_Y);
   lv_obj_set_style_bg_color(s_progress, C_PROGRESS_BG, 0);
   lv_obj_set_style_bg_opa(s_progress, LV_OPA_COVER, 0);
   lv_obj_set_style_radius(s_progress, BOOT_BAR_H / 2, 0);
-  lv_obj_set_style_bg_color(s_progress, C_PROGRESS_BAR, LV_PART_INDICATOR);
+  lv_obj_set_style_bg_color(s_progress, C_PROGRESS_BAR,
+                            LV_PART_INDICATOR);
   lv_obj_set_style_bg_opa(s_progress, LV_OPA_COVER, LV_PART_INDICATOR);
-  lv_obj_set_style_radius(s_progress, BOOT_BAR_H / 2, LV_PART_INDICATOR);
+  lv_obj_set_style_radius(s_progress, BOOT_BAR_H / 2,
+                          LV_PART_INDICATOR);
   lv_bar_set_range(s_progress, 0, 100);
   lv_bar_set_value(s_progress, 0, LV_ANIM_OFF);
 
-  /* 状态文字（进度条上方） */
+  /* Status label above the progress bar */
+
   s_status = lv_label_create(scr);
   lv_obj_set_style_text_color(s_status, C_STATUS_TEXT, 0);
   lv_obj_set_style_text_font(s_status, &zh_font_16, 0);
-  lv_label_set_text(s_status, "正在启动");
+  lv_label_set_text(s_status, BOOT_STATUS_TEXT);
   lv_obj_align(s_status, LV_ALIGN_CENTER, 0, BOOT_TEXT_Y);
 }
 
+/****************************************************************************
+ * Name: boot_screen_update
+ *
+ * Description:
+ *   Advance the boot progress bar and refresh the status text.
+ *
+ * Input Parameters:
+ *   percent - Progress percentage (clamped to 0..100; negative clamps
+ *             to 0).
+ *   status  - New status text, or NULL to keep the current text.
+ *
+ ****************************************************************************/
+
 void boot_screen_update(int percent, const char *status)
 {
   if (s_progress != NULL)