Add unified relay command endpoint

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

@@ -91,7 +91,14 @@ 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 relay(id,on){
-  try{await fetch(`/relay/${id}/${on?"on":"off"}`); await load()}catch(e){}
+  try{
+    await fetch("/relay/set",{
+      method:"POST",
+      headers:{"Content-Type":"application/json"},
+      body:JSON.stringify({id:id,state:on})
+    });
+    await load();
+  }catch(e){}
 }
 function render(data){
   $("conn").textContent="Live";
@@ -1124,6 +1131,36 @@ void handleSelectBms() {
     server.send(200, "application/json", output);
 }
 
+
+void handleSetRelayPost() {
+    DynamicJsonDocument doc(512);
+    DeserializationError error = deserializeJson(doc, server.arg("plain"));
+
+    if (error) {
+        server.send(400, "application/json", "{\"ok\":false,\"error\":\"invalid_json\"}");
+        return;
+    }
+
+    String relayId = doc["id"] | "";
+    bool state = doc["state"] | false;
+
+    if (!setRelayById(relayId, state)) {
+        server.send(404, "application/json", "{\"ok\":false,\"error\":\"unknown_relay\"}");
+        return;
+    }
+
+    DynamicJsonDocument response(512);
+    response["type"] = "relay_response";
+    response["ok"] = true;
+    response["relay"] = relayId;
+    response["state"] = state;
+    response["enabled"] = state;
+
+    String output;
+    serializeJson(response, output);
+    server.send(200, "application/json", output);
+}
+
 void handleGenericRelayRoute() {
     String uri = server.uri();
     String prefix = "/relay/";
@@ -1220,6 +1257,7 @@ void setup() {
     });
 
     server.on("/status", handleStatus);
+    server.on("/relay/set", HTTP_POST, handleSetRelayPost);
     server.on("/relay/relay_1/on", HTTP_GET, handleGenericRelayRoute);
     server.on("/relay/relay_1/off", HTTP_GET, handleGenericRelayRoute);
     server.on("/relay/relay_2/on", HTTP_GET, handleGenericRelayRoute);