fix(review): address PR #105 review follow-ups

- src/log.c: log_stderr_init no longer closes STDERR_FILENO immediately
  after dup2(). The previous 'close(dup_fd)' closed fd 2 because dup2
  returns newfd on success; the in-app stderr capture pipe was silently
  dead, dropping libstrophe/openssl error output. Close the original
  stderr_pipe[1] instead and remember that the write end now lives at
  STDERR_FILENO so _log_stderr_close stays correct.

- src/database_sqlite.c: NULL-check sqlite3_mprintf result before
  passing it to sqlite3_exec in the DbVersion bootstrap path.

- src/tools/editor.c: drop three orphan #includes (<fcntl.h>,
  <pthread.h>, <readline/readline.h>) left behind when 9b03e3a50
  removed the async-editor path.

- src/xmpp/jid.c: match the g_new0 allocation in jid_create with
  g_free in jid_destroy. Same behaviour on glibc but stops being a
  foot-gun under custom glib allocators.

Verified with ci-build.sh in Debian docker: all 4 configs pass
(644/0, 605/0, 605/0, 644/0 unit + 130/0 functional).

src/tools/editor.c

@@ -9,14 +9,11 @@
  * SPDX-License-Identifier: GPL-3.0-or-later WITH OpenSSL-exception
  */
 
-#include <fcntl.h>
 #include <glib.h>
 #include <errno.h>
-#include <stdio.h> // necessary for readline
-#include <readline/readline.h>
+#include <stdio.h>
 #include <sys/wait.h>
 #include <unistd.h>
-#include <pthread.h>
 #include <signal.h>
 
 #include "config/files.h"