Merge branch 'master' into merge/upstream-full

Resolve conflicts after master gained the flat-file database backend,
AI client, and other cproof-fork features:

- CHANGELOG: keep cproof-fork unreleased section atop full upstream
  history (0.17.0 / 0.16.0 / 0.15.1)
- src/command/cmd_ac.c: keep both upstream spellcheck AC and cproof
  /history switch|verify|export|import autocompletion
- src/config/preferences.c: merge upstream [spellcheck] group with the
  cproof [ai]/[ai/<provider>] groups
- src/database.c: take master (thin dispatcher); upstream SQLite
  improvements (v3 migration, auto_gchar) belong in database_sqlite.c
  and will land in a follow-up commit
- src/tools/autocomplete.c: take upstream unescape of search_str
- src/ui/statusbar.c: keep guint signatures (per project preference)
  and adapt _status_bar_draw_dbbackend to guint as well
- src/xmpp/jid.c: combine the new jid_is_valid/jid_is_valid_user_jid
  with the "(null)" legacy-placeholder guard in
  jid_create_from_bare_and_resource; use auto_gchar
- tests/functionaltests/proftest.c: keep unsigned-safe pre-check on
  output_len before subtracting OUTPUT_BUF_SIZE
- tests/unittests/unittests.c: keep upstream subdirectory include
  layout plus cproof-only test_ai_client/database_export/database_stress
- tests/unittests/test_jid.c: drop orphan top-level copy (the
  restructured version lives in tests/unittests/xmpp/test_jid.c)

Upstream is included up to 1ac05754b (release 0.18.0 era). Follow-up:
pull 1ac05754b..upstream/master (esp. 42a849d16 db migration fix and
4749645c7 receipt-request restore), and adapt the SQLite improvements
into database_sqlite.c.

src/event/client_events.c

@@ -11,8 +11,10 @@
 #include "config.h"
 
 #include <stdlib.h>
+#include <assert.h>
 #include <glib.h>
 
+#include "ai/ai_client.h"
 #include "log.h"
 #include "chatlog.h"
 #include "database.h"
@@ -21,7 +23,7 @@
 #include "event/common.h"
 #include "plugins/plugins.h"
 #include "ui/inputwin.h"
-#include "ui/window_list.h"
+#include "ui/window.h"
 #include "xmpp/chat_session.h"
 #include "xmpp/session.h"
 #include "xmpp/xmpp.h"
@@ -265,3 +267,24 @@ allow_unencrypted_message(ProfChatWin* chatwin, const char* const msg)
     win_println((ProfWin*)chatwin, THEME_ERROR, "-", "Message not sent: invalid encryption mode (%s). Use '/force-encryption policy resend-to-confirm'.", force_enc_mode);
     return FALSE;
 }
+
+void
+cl_ev_send_ai_msg(ProfAiWin* aiwin, const char* const message, const char* const id)
+{
+    if (!aiwin || !message) {
+        return;
+    }
+
+    assert(aiwin->memcheck == PROFAIWIN_MEMCHECK);
+
+    if (!aiwin->session) {
+        log_error("[AI] AI session not initialized");
+        return;
+    }
+
+    // Display user message in AI window.
+    win_print_outgoing(&aiwin->window, ">>", id, NULL, message);
+
+    // Send to AI provider.
+    ai_send_prompt(aiwin->session, message, aiwin);
+}

src/event/client_events.h

@@ -25,6 +25,7 @@ void cl_ev_send_msg(ProfChatWin* chatwin, const char* const msg, const char* con
 void cl_ev_send_muc_msg_corrected(ProfMucWin* mucwin, const char* const msg, const char* const oob_url, gboolean correct_last_msg);
 void cl_ev_send_muc_msg(ProfMucWin* mucwin, const char* const msg, const char* const oob_url);
 void cl_ev_send_priv_msg(ProfPrivateWin* privwin, const char* const msg, const char* const oob_url);
+void cl_ev_send_ai_msg(ProfAiWin* aiwin, const char* const message, const char* const id);
 
 // Checks if an unencrypted message can be sent based on encryption preferences.
 // Returns TRUE if allowed, FALSE if blocked.