fix(tcp): MUX模式网口失联 — 对端关闭时用tcp_abort替代tcp_close避免TIME_WAIT耗尽pcb池

根因: tcp_close()将对端关闭的pcb推入TIME_WAIT(120s), 占用MEMP_TCP_PCB池(仅4个),
多连接同时断开后pcb池耗尽, tcp_new()返回NULL, 新连接无法建立直到120s超时释放。

核心修复:
- tcp_server/client: 对端关闭(p=NULL)时tcp_abort替代tcp_close, pcb立即释放
- ch390_runtime: PKT_ERR恢复强制OR上RCR_RXEN(与WCH官方一致)
- ch390_runtime: TX连续超时3次自动emergency reset
- ch390_runtime: 每5秒health_check读VID验证芯片存活
- main: App_StartLinksIfNeeded失败时不标记g_links_started, 允许重试
- main: MUX逐帧RTT printf改为#if DEBUG门控, 减少主循环延迟
- uart_trans: MUX帧解析改为先搜0x7E再消费header, 非法帧只丢1字节

App/uart_trans.c

@@ -297,7 +297,8 @@ void uart_trans_tx_cplt_handler(uart_channel_t channel)
 
 bool uart_mux_try_extract_frame(uart_channel_t channel, uart_mux_frame_t *frame)
 {
-    uint8_t header[5];
+    uint8_t sync_byte;
+    uint8_t header[4];
     uint16_t available;
     uint16_t payload_len;
 
@@ -310,14 +311,25 @@ bool uart_mux_try_extract_frame(uart_channel_t channel, uart_mux_frame_t *frame)
         return false;
     }
 
-    if (uart_trans_read(channel, header, sizeof(header)) != sizeof(header)) {
+    /* Scan for SYNC byte (0x7E) — discard non-matching bytes one at a time */
+    if (uart_trans_read(channel, &sync_byte, 1u) != 1u) {
         return false;
     }
-    if (header[0] != UART_MUX_SYNC) {
+    if (sync_byte != UART_MUX_SYNC) {
         return false;
     }
 
-    payload_len = (uint16_t)(((uint16_t)header[1] << 8) | header[2]);
+    /* Need at least: 2(len) + 1(src) + 1(dst) + payload + 1(tail) = 5 + payload */
+    available = uart_trans_rx_available(channel);
+    if (available < 4u) {
+        return false;
+    }
+
+    if (uart_trans_read(channel, header, sizeof(header)) != sizeof(header)) {
+        return false;
+    }
+
+    payload_len = (uint16_t)(((uint16_t)header[0] << 8) | header[1]);
     if (payload_len > sizeof(frame->payload)) {
         return false;
     }
@@ -325,8 +337,8 @@ bool uart_mux_try_extract_frame(uart_channel_t channel, uart_mux_frame_t *frame)
         return false;
     }
 
-    frame->src_id = header[3];
-    frame->dst_mask = header[4];
+    frame->src_id = header[2];
+    frame->dst_mask = header[3];
     frame->payload_len = payload_len;
     if (payload_len > 0u) {
         if (uart_trans_read(channel, frame->payload, payload_len) != payload_len) {