gui: show the source filename in Library and Store details

Add a muted, selectable filename line under the title in both details
panels, with the full path as its tooltip (archive name in the Store,
disc/ISO filename in the Library).

app/gui.py

@@ -611,6 +611,12 @@ class GameDetailsPanel(QWidget):
         self.subtitle.setStyleSheet("color: #999;")
         self.layout.addWidget(self.subtitle)
 
+        self.filename = QLabel("")
+        self.filename.setStyleSheet("color: #777;")
+        self.filename.setWordWrap(True)
+        self.filename.setTextInteractionFlags(Qt.TextSelectableByMouse)
+        self.layout.addWidget(self.filename)
+
         self.layout.addSpacing(8)
         self.meta_grid = QGridLayout()
         self.meta_grid.setHorizontalSpacing(14)
@@ -676,6 +682,9 @@ class GameDetailsPanel(QWidget):
         self.system = item.get("system")
         self._ps1_kind = item.get("ps1_kind")
         path = item.get("path") or ""
+        self.filename.setText(Path(path).name if path else "")
+        self.filename.setToolTip(path)
+        self.filename.setVisible(bool(path))
         is_ps1 = item.get("system") == "ps1"
         is_ps1_disc = is_ps1 and item.get("ps1_kind") == "disc"
         self.play_btn.setEnabled(
@@ -1412,6 +1421,12 @@ class StoreDetailsPanel(QWidget):
         self.subtitle.setStyleSheet("color: #999;")
         self.layout.addWidget(self.subtitle)
 
+        self.filename = QLabel("")
+        self.filename.setStyleSheet("color: #777;")
+        self.filename.setWordWrap(True)
+        self.filename.setTextInteractionFlags(Qt.TextSelectableByMouse)
+        self.layout.addWidget(self.filename)
+
         self.layout.addSpacing(8)
         self.meta_grid = QGridLayout()
         self.meta_grid.setHorizontalSpacing(14)
@@ -1445,6 +1460,11 @@ class StoreDetailsPanel(QWidget):
 
     def set_item(self, item):
         self._item = item
+        fpath = item.get("path") or ""
+        fname = Path(fpath).name if fpath else (item.get("name") or "")
+        self.filename.setText(fname)
+        self.filename.setToolTip(fpath or fname)
+        self.filename.setVisible(bool(fname))
         self.title.setText(item.get("title_override") or store.display_name(item["name"]))
         parts = []
         size = item.get("size")