fix(mam, log): improve datetime handling and memory management in MAM and log fetching

- Introduce static helper `_truncate_datetime_suffix()` to safely trim datetime strings, removing unwanted suffixes like timezone offsets
- Replace manual string management with auto_gchar and g_strdup for safer, clearer ownership and to prevent leaks
- Add safety checks and logging warnings for unexpected datetime string lengths or null pointers
- Refactor _mam_rsm_id_handler to use the helper function and updated string handling
- Change log_database_get_previous_chat parameters for consistent ownership semantics, avoiding double frees and mem leaks
- Overall improve stability and prevent memory leaks during log database queries

src/xmpp/iq.c

@@ -2752,6 +2752,22 @@ iq_mam_request(ProfChatWin* win, GDateTime* enddate)
     return;
 }
 
+// Trim the last 3 characters from the datetime string to remove unwanted suffix (timezone offset)
+static void
+_truncate_datetime_suffix(gchar* str)
+{
+    if (!str) {
+        log_warning("_truncate_datetime_suffix(): unexpected null datetime string");
+        return;
+    }
+    size_t len = strlen(str);
+    if (len >= 3) {
+        str[len - 3] = '\0';
+    } else {
+        log_warning("_truncate_datetime_suffix(): unexpected short datetime string: %s", str);
+    }
+}
+
 static int
 _mam_rsm_id_handler(xmpp_stanza_t* const stanza, void* const userdata)
 {
@@ -2773,17 +2789,17 @@ _mam_rsm_id_handler(xmpp_stanza_t* const stanza, void* const userdata)
 
             buffer_remove_entry(window->layout->buffer, 0);
 
-            auto_char char* start_str = NULL;
+            auto_gchar gchar* start_str = NULL;
             if (data->start_datestr) {
-                start_str = strdup(data->start_datestr);
+                start_str = g_strdup(data->start_datestr);
                 // Convert to iso8601
-                start_str[strlen(start_str) - 3] = '\0';
+                _truncate_datetime_suffix(start_str);
             }
-            char* end_str = NULL;
+            auto_gchar gchar* end_str = NULL;
             if (data->end_datestr) {
-                end_str = strdup(data->end_datestr);
+                end_str = g_strdup(data->end_datestr);
                 // Convert to iso8601
-                end_str[strlen(end_str) - 3] = '\0';
+                _truncate_datetime_suffix(end_str);
             }
 
             if (is_complete || !data->fetch_next) {