Add BMS polling controls to embedded dashboard

firmware/esp32/overland-controller/overland-controller.ino

@@ -66,6 +66,11 @@ const char INDEX_HTML[] PROGMEM = R"rawliteral(
         <div class="row"><span class="muted">Battery temp</span><span class="v" id="battTemp">--</span></div>
         <div class="row"><span class="muted">Cell delta</span><span class="v" id="delta">--</span></div>
         <div class="row"><span class="muted">Cycles</span><span class="v" id="cycles">--</span></div>
+        <div class="row"><span class="muted">BMS Polling</span><span class="v" id="bmsEnabledText">--</span></div>
+        <div class="relayBtns">
+          <button onclick="setBmsEnabled(true)">Enable BMS</button>
+          <button class="off" onclick="setBmsEnabled(false)">Disable BMS</button>
+        </div>
       </section>
 
       <section class="card span6">
@@ -112,6 +117,18 @@ const $=id=>document.getElementById(id);
 function fmt(n,d=1){return typeof n==="number"?n.toFixed(d):"--"}
 function temp(v){return typeof v==="number"?fmt(v,1)+"°F":"Offline"}
 function clsAlarm(v){return v?"bad":"good"}
+async function setBmsEnabled(enabled){
+  try{
+    await fetch("/config/bms",{
+      method:"POST",
+      headers:{"Content-Type":"application/json"},
+      body:JSON.stringify({enabled:enabled})
+    });
+    await fetch("/config/save",{method:"POST"});
+    await load();
+  }catch(e){}
+}
+
 async function relay(id,on){
   try{
     await fetch("/relay/set",{
@@ -137,6 +154,8 @@ function render(data){
   $("battTemp").textContent=temp(b.temperature_f);
   $("delta").textContent=(typeof b.cell_delta_mv==="number"?b.cell_delta_mv:"--")+" mV";
   $("cycles").textContent=b.cycle_count??"--";
+  const bmsCfg=data.config?.bms||{};
+  $("bmsEnabledText").textContent=bmsCfg.enabled ? "Enabled" : "Disabled";
 
   $("temps").innerHTML=(data.temps||[]).map(t=>`
     <div class="item">