ESP32-S3 摄像头图传：固件 + Slint 客户端 + 共享协议

两块 ESP32-S3-WROOM-1-N16R8 图传板（DVP 接口接 OV2640/OV3660/OV5640），
向队伍客户端与裁判终端推 UDP 图传。固件是跑在 ESP-IDF 上的 Rust，用官方
esp32-camera 组件采集；客户端是 Rust + Slint 桌面程序。

三个 crate 各自独立构建：
  .            firmware，交叉编译到 Xtensa
  protocol/    线路格式与帧重组，两端共用，无 ESP-IDF 依赖，有单元测试
  client/      Slint 桌面客户端

视频走 UDP 而非 TCP：实测传感器产出 22 fps，TCP MJPEG 只送出 1.9 fps，
且只占用链路能力的 1%——链路是空的，帧堵在队头阻塞后面等一个实时画面
等不起的重传计时器。改为独立数据报、不重传、缺片丢整帧后达到 20.8 fps。

发现是双向的：板子每 2 秒广播 Hello，客户端广播 Subscribe，板子据此定向
推流。板子身份由 MAC 派生，重启不变，所以客户端可以把绑定存进配置。

裁判端同时收两块板子（每个发送方一个重组器），队伍端绑定其中一块并只显示
自己那一边的血量。装甲板接口已预留（ArmorSource trait + ARMOR_PORT），
当前无数据源，界面显示占位符。

vendor 了 esp32-camera 2.1.7：组件注册表的版本求解器找不到它，且需要打一处
补丁（见 components/esp32-camera/target/esp32s3/ll_cam.c）。

.gitignore 三条 target/ 都锚定在根目录，因为 protocol/ 与 client/ 各自也是
独立 crate；而 components/esp32-camera/target/ 是上游的按芯片分目录，里面是
源码，必须保留。

components/esp32-camera/CMakeLists.txt

@@ -0,0 +1,110 @@
+# get IDF version for comparison
+set(idf_version "${IDF_VERSION_MAJOR}.${IDF_VERSION_MINOR}")
+
+set(priv_requires "")
+
+# set conversion sources
+set(srcs
+  conversions/yuv.c
+  conversions/to_jpg.cpp
+  conversions/to_bmp.c
+  conversions/jpge.cpp
+  )
+
+set(priv_include_dirs
+  conversions/private_include
+  )
+
+set(include_dirs
+  driver/include
+  conversions/include
+  )
+
+# set driver sources only for supported platforms
+if(IDF_TARGET STREQUAL "esp32" OR IDF_TARGET STREQUAL "esp32s2" OR IDF_TARGET STREQUAL "esp32s3")
+  list(APPEND srcs
+    driver/esp_camera.c
+    driver/esp_camera_af.c
+    driver/cam_hal.c
+    driver/sensor.c
+    sensors/ov2640.c
+    sensors/ov3660.c
+    sensors/ov5640.c
+    sensors/ov5640_af.c
+    sensors/ov7725.c
+    sensors/ov7670.c
+    sensors/nt99141.c
+    sensors/gc0308.c
+    sensors/gc2145.c
+    sensors/gc032a.c
+    sensors/bf3005.c
+    sensors/bf20a6.c
+    sensors/sc101iot.c
+    sensors/sc030iot.c
+    sensors/sc031gs.c
+    sensors/mega_ccm.c
+    sensors/hm1055.c
+    sensors/hm0360.c
+    )
+
+  list(APPEND priv_include_dirs
+    driver/private_include
+    sensors/private_include
+    target/private_include
+    )
+
+  if(IDF_TARGET STREQUAL "esp32")
+    list(APPEND srcs
+      target/xclk.c
+      target/esp32/ll_cam.c
+      )
+  endif()
+
+  if(IDF_TARGET STREQUAL "esp32s2")
+    list(APPEND srcs
+      target/xclk.c
+      target/esp32s2/ll_cam.c
+      )
+
+    list(APPEND priv_include_dirs
+      target/esp32s2/private_include
+      )
+  endif()
+
+  if(IDF_TARGET STREQUAL "esp32s3")
+    list(APPEND srcs
+      target/esp32s3/ll_cam.c
+      )
+  endif()
+
+  list(APPEND priv_requires freertos nvs_flash esp_mm)
+
+  set(min_version_for_esp_timer "4.2")
+  if (idf_version VERSION_GREATER_EQUAL min_version_for_esp_timer)
+    list(APPEND priv_requires esp_timer)
+  endif()
+
+  # include the SCCB I2C driver
+  # this uses either the legacy I2C API or the newer version from IDF v5.4
+  # as this features a method to obtain the I2C driver from a port number
+  if (idf_version VERSION_GREATER_EQUAL "5.4" AND NOT CONFIG_SCCB_HARDWARE_I2C_DRIVER_LEGACY)
+    list(APPEND srcs driver/sccb-ng.c)
+  else()
+    list(APPEND srcs driver/sccb.c)
+  endif()
+
+endif()
+
+set(req driver)
+if (idf_version VERSION_GREATER_EQUAL "6.0")
+  list(APPEND priv_requires esp_driver_gpio esp_driver_spi esp_driver_i2c)
+  list(APPEND req esp_driver_ledc esp_hal_clock)
+endif()
+
+idf_component_register(
+  SRCS ${srcs}
+  INCLUDE_DIRS ${include_dirs}
+  PRIV_INCLUDE_DIRS ${priv_include_dirs}
+  REQUIRES ${req}
+  PRIV_REQUIRES ${priv_requires}
+)