feat(gml670x4): 所有协议帧添加 CRC-8/MAXIM 校验

使用 Zephyr crc8() 对帧头之后的载荷计算 CRC，上行发送前填充、
下行接收时校验不通过则丢弃并告警。同步更新协议文档。

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/ble_transport.c

@@ -78,6 +78,11 @@ static void nus_received_cb(struct bt_conn *conn, const uint8_t *data, uint16_t
     switch (data[2]) {
     case PROTO_TYPE_RESISTANCE:
         if (len >= sizeof(struct resistance_frame_t)) {
+            uint8_t crc = crc8(data + 2, sizeof(struct resistance_frame_t) - 3, 0x31, 0x00, true);
+            if (data[sizeof(struct resistance_frame_t) - 1] != crc) {
+                LOG_WRN("Resistance frame CRC mismatch");
+                break;
+            }
             union resistance_pkt_t pkt;
             memcpy(pkt.bytes, data, sizeof(struct resistance_frame_t));
             resistance_K   = pkt.frame.K;
@@ -90,6 +95,11 @@ static void nus_received_cb(struct bt_conn *conn, const uint8_t *data, uint16_t
         break;
     case PROTO_TYPE_SPOTTER:
         if (len >= sizeof(struct spotter_frame_t)) {
+            uint8_t crc = crc8(data + 2, sizeof(struct spotter_frame_t) - 3, 0x31, 0x00, true);
+            if (data[sizeof(struct spotter_frame_t) - 1] != crc) {
+                LOG_WRN("Spotter frame CRC mismatch");
+                break;
+            }
             union spotter_pkt_t pkt;
             memcpy(pkt.bytes, data, sizeof(struct spotter_frame_t));
             spotter_threshold = pkt.frame.threshold;
@@ -99,6 +109,11 @@ static void nus_received_cb(struct bt_conn *conn, const uint8_t *data, uint16_t
         break;
     case PROTO_TYPE_HEARTBEAT:
         if (len >= sizeof(struct heartbeat_frame_t)) {
+            uint8_t crc = crc8(data + 2, sizeof(struct heartbeat_frame_t) - 3, 0x31, 0x00, true);
+            if (data[sizeof(struct heartbeat_frame_t) - 1] != crc) {
+                LOG_WRN("Heartbeat frame CRC mismatch");
+                break;
+            }
             last_heartbeat_ms = k_uptime_get();
             LOG_DBG("RX Heartbeat");
         }

src/main.c

@@ -23,9 +23,8 @@ int main(void) {
     ble_transport_adv_start();
 
     if (sensor_init()) return 0;
-    while (1) {
-        k_sleep(K_SECONDS(1));
-    }
+
+    k_sleep(K_FOREVER);
 
     return 0;
 }

src/sensor.c

@@ -163,6 +163,7 @@ static void sensor_thread_fn(void *p1, void *p2, void *p3) {
         pkt.frame.cop_x = cop_x;
         pkt.frame.cop_y = cop_y;
         pkt.frame.force = force;
+        pkt.frame.crc   = crc8(pkt.bytes + 2, sizeof(pkt.bytes) - 3, 0x31, 0x00, true);
 
         /* 发送 */
         ble_transport_send(pkt.bytes, sizeof(pkt.bytes));