Pre-visualize the estimated Sud course in the Automatic tab

Adds a static forecast plot to the (previously empty) Automatic tab,
showing the planned temperature course derived from a schedule's
declared ramp rates and hold durations alone (no plant/controller
model - just how long the schedule itself says each step takes).

The client now requests the schedule via Download right after
connecting, routing the reply to the forecast instead of a save
dialog since sud_download_path is only set for the user-initiated
download. SudTask also echoes the just-applied document back after a
successful Upload, so editing the schedule refreshes the forecast
without an extra round trip.

client/main_window.py

@@ -246,6 +246,12 @@ class Ui_MainWindow(object):
         self.horizontalTabWidget.addTab(self.horizontalTabWidgetPage1, "")
         self.tab = QtWidgets.QWidget()
         self.tab.setObjectName("tab")
+        self.verticalLayout_forecast = QtWidgets.QVBoxLayout(self.tab)
+        self.verticalLayout_forecast.setObjectName("verticalLayout_forecast")
+        self.widget_plot_forecast = QtWidgets.QWidget(self.tab)
+        self.widget_plot_forecast.setMinimumSize(QtCore.QSize(0, 400))
+        self.widget_plot_forecast.setObjectName("widget_plot_forecast")
+        self.verticalLayout_forecast.addWidget(self.widget_plot_forecast)
         self.horizontalTabWidget.addTab(self.tab, "")
         self.tab_2 = QtWidgets.QWidget()
         self.tab_2.setObjectName("tab_2")