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/xmpp/message.c

@@ -353,7 +353,7 @@ message_handlers_init(void)
 ProfMessage*
 message_init(void)
 {
-    ProfMessage* message = calloc(1, sizeof(ProfMessage));
+    ProfMessage* message = g_new0(ProfMessage, 1);
 
     message->enc = PROF_MSG_ENC_NONE;
     message->trusted = true;