split the selection panel into one card per kind of selection

src/ui/selection/HqContent.cpp

@@ -0,0 +1,42 @@
+#include "HqContent.h"
+
+#include <QLabel>
+#include <QVBoxLayout>
+
+#include "EntityAdmin.h"
+#include "HealthComponent.h"
+#include "HqProxyComponent.h"
+#include "SelectionNames.h"
+#include "Simulation.h"
+
+HqContent::HqContent(const SelectionContext& context, const SelectionRequest& request,
+                     QWidget* parent)
+    // The HQ is placed before the game starts and can never be deconstructed
+    // (REQ-BLD-DECONSTRUCT), so it is never a construction site.
+    : SelectionContent(context, std::nullopt, parent)
+{
+    m_stockLabel = new QLabel(this);
+    m_hpLabel    = new QLabel(this);
+    getRuntimeLayout()->addWidget(m_stockLabel);
+    getRuntimeLayout()->addWidget(m_hpLabel);
+
+    setBuildingIdentity(BuildingType::Hq, getBuildingTypeName(BuildingType::Hq));
+}
+
+void HqContent::refreshRuntime()
+{
+    m_stockLabel->setText(
+        tr("Building blocks: %1").arg(getContext().sim->getBuildingBlocksStock()));
+
+    // The HQ's health lives on its proxy entity, not on the building
+    // (REQ-HQ-STATS, REQ-UI-HP-BARS).
+    EntityAdmin& admin = getContext().sim->getAdmin();
+    admin.forEach<HqProxyComponent, HealthComponent>(
+        [this](entt::entity /*entity*/, const HqProxyComponent& /*proxy*/,
+               const HealthComponent& health)
+        {
+            m_hpLabel->setText(tr("HP: %1 / %2")
+                .arg(static_cast<int>(health.hp + 0.5f))
+                .arg(static_cast<int>(health.maxHp + 0.5f)));
+        });
+}