refactor: replace calloc with g_new0 for struct allocations

Migrate structure allocations from calloc to glibs g_new0 macro to
improve type safety and memory robustness.

* Type Safety: The macro takes the type name directly, ensuring the
  allocated size always matches the pointer type.
* Static Analysis: It guarantees a non-NULL return by aborting on
  failure, which silences -fanalyzer warnings regarding potential NULL
  pointer dereferences.
* Readability: Removes redundant sizeof() calls and is the glib way

src/ui/statusbar.c

@@ -102,7 +102,7 @@ status_bar_init(void)
     statusbar->prompt = NULL;
     statusbar->fulljid = NULL;
     statusbar->tabs = g_hash_table_new_full(g_direct_hash, g_direct_equal, NULL, (GDestroyNotify)_destroy_tab);
-    StatusBarTab* console = calloc(1, sizeof(StatusBarTab));
+    StatusBarTab* console = g_new0(StatusBarTab, 1);
     console->window_type = WIN_CONSOLE;
     console->identifier = strdup("console");
     console->display_name = NULL;