fix: event listener leak and ArduinoJson buffer sizes

- Move visibilitychange listener out of connectDataWs() to prevent
  duplicate listeners accumulating on each WS reconnect
- Increase ArduinoJson document sizes: full sync 512→640, diff 256→384,
  initial sync 512→640 for safety margin with 25+ fields

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

Author: basmeerman

SmartEVSE-3/data/app.js

@@ -172,19 +172,19 @@ function connectDataWs() {
         /* Resume polling while WS is disconnected */
         loadData();
     };
-
-    /* Pause/resume on visibility change */
-    document.addEventListener('visibilitychange', function() {
-        if (document.hidden) {
-            if (dataWs) dataWs.close();
-        } else if (!dataWs || dataWs.readyState !== WebSocket.OPEN) {
-            clearTimeout(dataWsReconnectTimer);
-            dataWsReconnectAttempts = 0;
-            connectDataWs();
-        }
-    });
 }
 
+/* Visibility-aware pause/resume for data WS (registered once) */
+document.addEventListener('visibilitychange', function() {
+    if (document.hidden) {
+        if (dataWs) dataWs.close();
+    } else if (!dataWs || dataWs.readyState !== WebSocket.OPEN) {
+        clearTimeout(dataWsReconnectTimer);
+        dataWsReconnectAttempts = 0;
+        connectDataWs();
+    }
+});
+
 /* ========== Theme (dark mode) ========== */
 function getTheme() {
     var stored = localStorage.getItem('evse_theme');

SmartEVSE-3/src/network_common.cpp

@@ -208,7 +208,7 @@ static void ws_data_timer_fn(void *arg) {
     if (fullSync) wsDataSyncCounter = 0;
 
     // Build JSON
-    DynamicJsonDocument doc(fullSync ? 512 : 256);
+    DynamicJsonDocument doc(fullSync ? 640 : 384);
 
     if (fullSync) {
         wsBuildFullState(doc);
@@ -1291,7 +1291,7 @@ static void fn_http_server(struct mg_connection *c, int ev, void *ev_data) {
             }
 
             // Send immediate full sync to newly connected client
-            DynamicJsonDocument doc(512);
+            DynamicJsonDocument doc(640);
             wsBuildFullState(doc);
             String json;
             serializeJson(doc, json);