hyprctl/layers: print pid for layershell clients (#9468)

Adds a `getPID()` fn to layershell to print it in `hyprctl layers`

src/debug/HyprCtl.cpp

@@ -479,9 +479,11 @@ static std::string layersRequest(eHyprCtlOutputFormat format, std::string reques
                     "y": {},
                     "w": {},
                     "h": {},
-                    "namespace": "{}"
+                    "namespace": "{}",
+                    "pid": {}
                 }},)#",
-                        (uintptr_t)layer.get(), layer->geometry.x, layer->geometry.y, layer->geometry.width, layer->geometry.height, escapeJSONStrings(layer->szNamespace));
+                        (uintptr_t)layer.get(), layer->geometry.x, layer->geometry.y, layer->geometry.width, layer->geometry.height, escapeJSONStrings(layer->szNamespace),
+                        layer->getPID());
                 }
 
                 trimTrailingComma(result);
@@ -512,8 +514,8 @@ static std::string layersRequest(eHyprCtlOutputFormat format, std::string reques
                 result += std::format("\tLayer level {} ({}):\n", layerLevel, levelNames[layerLevel]);
 
                 for (auto const& layer : level) {
-                    result += std::format("\t\tLayer {:x}: xywh: {} {} {} {}, namespace: {}\n", (uintptr_t)layer.get(), layer->geometry.x, layer->geometry.y, layer->geometry.width,
+                    result += std::format("\t\tLayer {:x}: xywh: {} {} {} {}, namespace: {}, pid: {}\n", (uintptr_t)layer.get(), layer->geometry.x, layer->geometry.y,
-                                          layer->geometry.height, layer->szNamespace);
+                                          layer->geometry.width, layer->geometry.height, layer->szNamespace, layer->getPID());
                 }
 
                 layerLevel++;

src/desktop/LayerSurface.cpp

@@ -584,3 +584,15 @@ int CLayerSurface::popupsCount() {
 MONITORID CLayerSurface::monitorID() {
     return monitor ? monitor->ID : MONITOR_INVALID;
 }
+
+pid_t CLayerSurface::getPID() {
+    pid_t PID = -1;
+
+    if (!layerSurface || !layerSurface->surface || !layerSurface->surface->getResource() || !layerSurface->surface->getResource()->resource() ||
+        !layerSurface->surface->getResource()->resource()->client)
+        return -1;
+
+    wl_client_get_credentials(layerSurface->surface->getResource()->resource()->client, &PID, nullptr, nullptr);
+
+    return PID;
+}

src/desktop/LayerSurface.hpp

@@ -61,6 +61,8 @@ class CLayerSurface {
     std::string                szNamespace = "";
     UP<CPopup>                 popupHead;
 
+    pid_t                      getPID();
+
     void                       onDestroy();
     void                       onMap();
     void                       onUnmap();