refactor: address PR #105 review feedback

Apply fixes, refactors and test additions requested by reviewer on PR #105.

Fixes:
- database: warn and notify user on duplicate archive_id instead of
  silently debug-logging it (R05).
- database: add missing '[' in "[DB Migration]" log prefix (R06).
- xmpp/resource: NULL-out name/status after g_free to avoid double-free
  via roster_list.c cleanup path (R09, R23).
- common: widen strtoi_range internal storage from int to long so that
  values in (INT_MAX, LONG_MAX] are rejected as out-of-range instead of
  being silently truncated on 64-bit platforms (R25).

Refactors:
- xmpp/message: extract _receive_omemo helper, removing three copies of
  the OMEMO receive block in groupchat / MUC-PM / chat handlers (R04).
- omemo: flatten deeply nested device-list processing via guard-clause
  continues (R11).
- tools/autocomplete: merge two nested ifs into a single && condition
  (R13).
- ui/titlebar: extract _show_trust_indicator and inline _wprintw_withattr
  wrapper, collapsing three near-identical trust-indicator blocks (R22).
- config/tlscerts: drop _checked_g_strdup wrapper; g_strdup is
  NULL-safe per glib documentation (R19).
- ui/inputwin: use auto_gchar for spellcheck word instead of manual
  g_free (R20).
- tools/editor: drop outdated "Deprecated synchronous" comment that
  no longer matches the callback-based implementation (R28).

Tests:
- tests/command/cmd_ac: rename segfaults_when_empty ->
  no_segfault_when_empty; expand cycling coverage to three files plus
  backward SHIFT-TAB traversal (R16, R17).
- tests/common: add strtoi_range overflow/underflow and strtol-parsing
  consistency tests (R25).
- tests/xmpp/jid: add test for '@' inside resourcepart per RFC 6122
  section 2.4 (R26).

Misc:
- xmpp/omemo: change omemo_error_to_string return type from char* to
  gchar* for glib consistency (R01).
- subprojects/libstrophe: point wrap-git at our fork at
  git.jabber.space/devs/libstrophe-gh (R24).
- RELEASE_GUIDE: drop "Updating website" section referring to an
  upstream site that is not ours (R18).

tests/unittests/command/test_cmd_ac.c

@@ -17,7 +17,7 @@ _create_test_file(const char* path)
 }
 
 void
-cmd_ac_complete_filepath__segfaults_when_empty(void** state)
+cmd_ac_complete_filepath__no_segfault_when_empty(void** state)
 {
     char* result = cmd_ac_complete_filepath("/sendfile ", "/sendfile", FALSE);
 
@@ -62,33 +62,44 @@ cmd_ac_complete_filepath__cycles_through_files(void** state)
     mkdir("test_dir", 0755);
     _create_test_file("test_dir/file1.txt");
     _create_test_file("test_dir/file2.txt");
+    _create_test_file("test_dir/file3.txt");
 
-    // 1st TAB
+    // TAB forward: file1 -> file2 -> file3
     char* res1 = cmd_ac_complete_filepath("/sendfile test_dir/file", "/sendfile", FALSE);
     assert_non_null(res1);
     assert_string_equal(res1, "/sendfile test_dir/file1.txt");
 
-    // 2nd TAB
     char* res2 = cmd_ac_complete_filepath(res1, "/sendfile", FALSE);
     assert_non_null(res2);
     assert_string_equal(res2, "/sendfile test_dir/file2.txt");
 
-    // 3rd TAB
     char* res3 = cmd_ac_complete_filepath(res2, "/sendfile", FALSE);
     assert_non_null(res3);
-    assert_string_equal(res3, "/sendfile test_dir/file1.txt");
+    assert_string_equal(res3, "/sendfile test_dir/file3.txt");
 
-    // SHIFT-TAB
-    char* res4 = cmd_ac_complete_filepath(res3, "/sendfile", TRUE);
+    // TAB wraps around: file3 -> file1
+    char* res4 = cmd_ac_complete_filepath(res3, "/sendfile", FALSE);
     assert_non_null(res4);
-    assert_string_equal(res4, "/sendfile test_dir/file2.txt");
+    assert_string_equal(res4, "/sendfile test_dir/file1.txt");
+
+    // SHIFT-TAB goes backward: file1 -> file3, then file3 -> file2
+    char* res5 = cmd_ac_complete_filepath(res4, "/sendfile", TRUE);
+    assert_non_null(res5);
+    assert_string_equal(res5, "/sendfile test_dir/file3.txt");
+
+    char* res6 = cmd_ac_complete_filepath(res5, "/sendfile", TRUE);
+    assert_non_null(res6);
+    assert_string_equal(res6, "/sendfile test_dir/file2.txt");
 
     free(res1);
     free(res2);
     free(res3);
     free(res4);
+    free(res5);
+    free(res6);
 
     remove("test_dir/file1.txt");
     remove("test_dir/file2.txt");
+    remove("test_dir/file3.txt");
     rmdir("test_dir");
 }

tests/unittests/command/test_cmd_ac.h

@@ -1,7 +1,7 @@
 #ifndef TESTS_TEST_CMD_AC_H
 #define TESTS_TEST_CMD_AC_H
 
-void cmd_ac_complete_filepath__segfaults_when_empty(void** state);
+void cmd_ac_complete_filepath__no_segfault_when_empty(void** state);
 void cmd_ac_complete_filepath__finds_files_in_current_dir(void** state);
 void cmd_ac_complete_filepath__finds_files_with_dot_slash(void** state);
 void cmd_ac_complete_filepath__cycles_through_files(void** state);