webui: preserve config edits during polling

tests/test_http_api_contract.py

@@ -460,3 +460,17 @@ def test_temp_config_lookup_is_available_to_http_handlers():
     helper_pos = source.index("int findTempConfigIndexById(")
     first_uart_guard_pos = source.index("#if DASHBOARD_UART_ENABLED")
     assert helper_pos < first_uart_guard_pos
+
+
+def test_embedded_webui_preserves_config_input_while_polling():
+    source = firmware_source()
+
+    assert "const configTouched={};" in source
+    assert "function markConfigFieldTouched(id)" in source
+    assert "function setConfigValue(id,value)" in source
+    assert "document.activeElement===el" in source
+    assert 'document.addEventListener("input"' in source
+    assert 'setConfigValue("apSsidInput"' in source
+    assert 'setConfigValue("deviceNameInput"' in source
+    assert 'setConfigValue("bmsNameInput"' in source
+    assert 'setConfigValue("tempEnabledCount"' in source