fix: address config injection and SIGCHLD handling

- Sanitize account names to prevent GKeyFile config injection by
  blocking special characters like #, \n, and \r.
- Ensure GLib's SIGCHLD handler is initialized before forking
  external editors to prevent zombie processes.
- Add missing error check for OMEMO random key generation.
- Replace hardcoded console tab ID with a named constant.
- Log invalid JIDs safely to prevent potential null pointer issues.

src/xmpp/jid.c

@@ -32,6 +32,7 @@ Jid*
 jid_create(const gchar* const str)
 {
     if (!jid_is_valid(str)) {
+        log_debug("[JID] invalid JID: '%s'", str ?: "(null)");
         return NULL;
     }