valgrind: GtkPopover suppressions

We get a ton of leaks from GTK.PopOver when we run the steps given in
the suppression file. I don't see how this could be us since we don't
create or do anything with the popover manually; its simply defined in
the Blueprint file.

valgrind.supp

@@ -13,6 +13,38 @@
 # You must gracefully exit Ghostty (do not SIGINT) by closing all windows
 # and quitting. Otherwise, we leave a number of GTK resources around.
 
+
+# Reproduction: 
+# 1. Launch Ghostty (no config)
+# 2. Right Click on the terminal
+# 3. Hover over "Split" to get a submenu
+# 4. Close menu by clicking away
+# 5. Exit
+#
+# The menu model and popover are fully defined in the blueprint so I don't
+# THINK we need to do any manual unrefing. But there's a lot of leaks here
+# so if someone wants to take a closer look I'd appreciate it.
+{
+   GTK PopOver Menu Model Leak
+   Memcheck:Leak
+   match-leak-kinds: possible
+   ...
+   fun:gtk_menu_section_box_insert_func
+   ...
+   fun:gtk_popover_menu_set_menu_model
+   ...
+}
+{
+   GTK/Blueprint Popover GSK Transform
+   Memcheck:Leak
+   match-leak-kinds: possible
+   ...
+   fun:gtk_popover_size_allocate
+   fun:gtk_widget_allocate
+   fun:gtk_popover_native_layout
+   ...
+}
+
 {
    GTK CSS Provider Leak
    Memcheck:Leak