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- tools/editor: drop outdated "Deprecated synchronous" comment that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).

src/xmpp/message.c

@@ -65,11 +65,30 @@ static void _handle_pubsub(xmpp_stanza_t* const stanza, xmpp_stanza_t* const eve
 static gboolean _handle_form(xmpp_stanza_t* const stanza);
 static gboolean _handle_jingle_message(xmpp_stanza_t* const stanza);
 static gboolean _should_ignore_based_on_silence(xmpp_stanza_t* const stanza);
+#ifdef HAVE_OMEMO
+static void _receive_omemo(xmpp_stanza_t* const stanza, ProfMessage* message);
+#endif
 
 #ifdef HAVE_LIBGPGME
 static xmpp_stanza_t* _ox_openpgp_signcrypt(xmpp_ctx_t* ctx, const char* const to, const char* const text);
 #endif // HAVE_LIBGPGME
 
+#ifdef HAVE_OMEMO
+static void
+_receive_omemo(xmpp_stanza_t* const stanza, ProfMessage* message)
+{
+    message->plain = omemo_receive_message(stanza, &message->trusted, &message->omemo_err);
+    if (message->omemo_err != OMEMO_ERR_NONE) {
+        message->enc = PROF_MSG_ENC_OMEMO;
+        if (message->plain == NULL) {
+            message->plain = omemo_error_to_string(message->omemo_err);
+        }
+    } else if (message->plain != NULL) {
+        message->enc = PROF_MSG_ENC_OMEMO;
+    }
+}
+#endif // HAVE_OMEMO
+
 static GHashTable* pubsub_event_handlers;
 
 gchar*
@@ -1088,15 +1107,7 @@ _handle_groupchat(xmpp_stanza_t* const stanza)
 
     // check omemo encryption
 #ifdef HAVE_OMEMO
-    message->plain = omemo_receive_message(stanza, &message->trusted, &message->omemo_err);
-    if (message->omemo_err != OMEMO_ERR_NONE) {
-        message->enc = PROF_MSG_ENC_OMEMO;
-        if (message->plain == NULL) {
-            message->plain = omemo_error_to_string(message->omemo_err);
-        }
-    } else if (message->plain != NULL) {
-        message->enc = PROF_MSG_ENC_OMEMO;
-    }
+    _receive_omemo(stanza, message);
 #endif
 
     if (!message->plain && !message->body) {
@@ -1253,15 +1264,7 @@ _handle_muc_private_message(xmpp_stanza_t* const stanza)
 
     // check omemo encryption
 #ifdef HAVE_OMEMO
-    message->plain = omemo_receive_message(stanza, &message->trusted, &message->omemo_err);
-    if (message->omemo_err != OMEMO_ERR_NONE) {
-        message->enc = PROF_MSG_ENC_OMEMO;
-        if (message->plain == NULL) {
-            message->plain = omemo_error_to_string(message->omemo_err);
-        }
-    } else if (message->plain != NULL) {
-        message->enc = PROF_MSG_ENC_OMEMO;
-    }
+    _receive_omemo(stanza, message);
 #endif
 
     message->timestamp = stanza_get_delay(stanza);
@@ -1428,15 +1431,7 @@ _handle_chat(xmpp_stanza_t* const stanza, gboolean is_mam, gboolean is_carbon, c
 
 #ifdef HAVE_OMEMO
     // check omemo encryption
-    message->plain = omemo_receive_message(stanza, &message->trusted, &message->omemo_err);
-    if (message->omemo_err != OMEMO_ERR_NONE) {
-        message->enc = PROF_MSG_ENC_OMEMO;
-        if (message->plain == NULL) {
-            message->plain = omemo_error_to_string(message->omemo_err);
-        }
-    } else if (message->plain != NULL) {
-        message->enc = PROF_MSG_ENC_OMEMO;
-    }
+    _receive_omemo(stanza, message);
 #endif
 
     xmpp_stanza_t* encrypted = xmpp_stanza_get_child_by_ns(stanza, STANZA_NS_ENCRYPTED);