refactor: optimize hash table iterations and fix security issues #58

- refactor(core): replace g_hash_table_get_keys with g_hash_table_iter_init
  * Eliminates temporary GList allocations
  * Improves iteration performance
  * Affected: connection.c, cmd_defs.c, cmd_funcs.c, omemo.c, gpg.c,
    disco.c, form.c, autocompleters.c, capabilities.c, callbacks.c

- fix(xmpp): correct queued_messages loop in connection.c:1031
  * Remove incorrect NULL check that prevented message storage
  * calloc zeros array, causing loop to skip immediately
  * Fixes dropped messages during reconnection with SM enabled

- fix(ui): prevent format string vulnerabilities in cons_show calls
  * Replace cons_show(variable) with cons_show("%s", variable)
  * Protects against format string attacks if variables contain %
  * Updated instances across cmd_funcs.c, connection.c, ox.c,
    console.c, core.c

src/plugins/autocompleters.c

@@ -141,18 +141,16 @@ autocompleters_complete(const char* const input, gboolean previous)
     while (curr_hash) {
         GHashTable* key_to_ac = curr_hash->data;
 
-        GList* keys = g_hash_table_get_keys(key_to_ac);
-        GList* curr = keys;
-        while (curr) {
-            result = autocomplete_param_with_ac(input, curr->data, g_hash_table_lookup(key_to_ac, curr->data), TRUE, previous);
+        GHashTableIter iter;
+        gpointer key, value;
+        g_hash_table_iter_init(&iter, key_to_ac);
+        while (g_hash_table_iter_next(&iter, &key, &value)) {
+            result = autocomplete_param_with_ac(input, key, value, TRUE, previous);
             if (result) {
                 g_list_free(ac_hashes);
-                g_list_free(keys);
                 return result;
             }
-            curr = g_list_next(curr);
         }
-        g_list_free(keys);
 
         curr_hash = g_list_next(curr_hash);
     }
@@ -162,22 +160,19 @@ autocompleters_complete(const char* const input, gboolean previous)
     curr_hash = filepath_hashes;
     while (curr_hash) {
         GHashTable* prefixes_hash = curr_hash->data;
-        GList* prefixes = g_hash_table_get_keys(prefixes_hash);
-        GList* curr_prefix = prefixes;
-        while (curr_prefix) {
-            char* prefix = curr_prefix->data;
+        GHashTableIter iter;
+        gpointer key, value;
+        g_hash_table_iter_init(&iter, prefixes_hash);
+        while (g_hash_table_iter_next(&iter, &key, &value)) {
+            char* prefix = (char*)key;
             if (g_str_has_prefix(input, prefix)) {
                 result = cmd_ac_complete_filepath(input, prefix, previous);
                 if (result) {
                     g_list_free(filepath_hashes);
-                    g_list_free(prefixes);
                     return result;
                 }
             }
-
-            curr_prefix = g_list_next(curr_prefix);
         }
-        g_list_free(prefixes);
 
         curr_hash = g_list_next(curr_hash);
     }