Implemented qt port + e2e

Client/streamhub-qt/PlotGrid.h

@@ -0,0 +1,61 @@
+/**
+ * @file PlotGrid.h
+ * @brief Resizable grid of PlotWidgets realising the selected PlotLayout.
+ *
+ * Built from nested QSplitters (rows of columns) so cells are user-resizable,
+ * mirroring the ImGui draggable separators. Holds up to kMaxPlotSlots plots,
+ * fans out the 60 Hz tick / model / pause notifications, and drives the
+ * history navigation (live ⇄ stored-X) for all visible plots.
+ */
+
+#pragma once
+
+#include "Model.h"
+
+#include <QWidget>
+#include <vector>
+
+namespace shq {
+
+class Hub;
+struct GlobalView;
+class PlotWidget;
+
+class PlotGrid : public QWidget {
+    Q_OBJECT
+public:
+    PlotGrid(Hub* hub, GlobalView* gv, QWidget* parent = nullptr);
+
+    void setLayout(PlotLayout l);
+    PlotLayout layout() const { return layout_; }
+    int numSlots() const { return layoutSlots(layout_); }
+
+    /** Visible plots (size == numSlots()). */
+    const std::vector<PlotWidget*>& plots() const { return plots_; }
+
+public Q_SLOTS:
+    void onModelChanged();
+    void onPauseChanged();
+    void tick();
+
+    /** History navigation helpers (operate on all visible plots). */
+    void goLive();
+    void setAllStoredX(double t0, double t1);
+    void panAll(double frac);            /* +right / -left, frac of span */
+    void jumpAllAgo(double secAgo);      /* set window ending secAgo before now */
+    bool anyNonLive() const;
+    /** Current stored range of the first non-live plot (false if all live). */
+    bool currentRange(double& t0, double& t1) const;
+
+private:
+    void rebuild();
+
+    Hub*        hub_;
+    GlobalView* gv_;
+    PlotLayout  layout_ = PlotLayout::k1x1;
+
+    std::vector<PlotWidget*> plots_;     /* currently mounted (== numSlots) */
+    std::vector<PlotWidget*> pool_;      /* all kMaxPlotSlots, persistent */
+};
+
+} /* namespace shq */