Add AP+STA WiFi manager and stabilize balancing

- Replace wifi.cpp/wifi.h with wifi_manager.cpp/wifi_manager.h: AP and STA
  run together, external WiFi credentials are stored in NVS and editable at
  /wifi, with optional static IP, 15s auto-reconnect, disconnect reason
  reporting, and build/version diagnostics
- Fix MPU6050 I2C port to I2C0 to match the board wiring
- Initialize distance_zeropoint at startup and on Robot Go! rising edge
- Clamp angle_zeropoint to +/-10 degrees to prevent balance-point drift
- Add DEBUG_DISABLE_YAW switch and periodic balance debug output
- Update WiFi setup instructions in README.md and README_CN.md

3.Software/wl_pro_robot/basic_web.h

@@ -280,6 +280,9 @@ const char basic_web[] PROGMEM = R"=====(
 <!-- onload 事件在页面载入完成后立即触发 -->
 <body onload="javascript:socket_init()">
     <h2>WL-PRO WiFi遥控模式</h2>
+    <div style="text-align:center;margin:-4px 0 10px;">
+        <a href="/wifi" style="color:#6495ed;font-size:15px;">WiFi 设置 / WiFi Settings</a>
+    </div>
     <div class="view2">
         <input type="checkbox" id="stable" class="switch" onclick="is_stable()" style="vertical-align:middle">Robot Go!</input>
     </div>
@@ -334,7 +337,7 @@ const char basic_web[] PROGMEM = R"=====(
         function socket_init() {
             // 初始化websocket客户端
             //socket = new WebSocket('ws://' + '192.168.4.1' + ':81/'); // AP模式
-            socket = new WebSocket('ws://' + window.location.hostname + ':81/'); // sta模式
+            socket = new WebSocket('ws://' + window.location.hostname + ':81/'); // AP/STA通用
         }
 
         function setroll() {