feat(omemo): suppress repetitive missing device ID warnings

When sending OMEMO messages, we print a warning message for every
participant without a device ID on every single send:

```
Can't find a OMEMO device id for my@jid.org
```

This clutters the UI due to the high volume of repetitive information.

This is solved by tracking suppressed warnings within the window
structure. A warning for a specific JID and type is only shown once
per window context.

Suppression state is stored in the base ProfWin structure and managed
via helper functions (win_warn_needed, win_warn_sent). The state is
lazily initialized to save resources and automatically cleaned up when
the window is closed.

Warnings are explicitly reset when an OMEMO session is started or
ended to ensure users see fresh alerts when toggling encryption.

src/command/cmd_funcs.c

@@ -57,6 +57,7 @@
 #include "plugins/plugins.h"
 #include "ui/inputwin.h"
 #include "ui/ui.h"
+#include "ui/window.h"
 #include "ui/window_list.h"
 #include "xmpp/avatar.h"
 #include "xmpp/chat_session.h"
@@ -8456,6 +8457,7 @@ cmd_omemo_start(ProfWin* window, const char* const command, gchar** args)
         win_println((ProfWin*)chatwin, THEME_DEFAULT, "!", "Initiating OMEMO session with %s...", chatwin->barejid);
         omemo_start_session(chatwin->barejid);
         chatwin->is_omemo = TRUE;
+        win_clear_warned_jids((ProfWin*)chatwin);
     } else if (window->type == WIN_MUC) {
         ProfMucWin* mucwin = (ProfMucWin*)window;
         assert(mucwin->memcheck == PROFMUCWIN_MEMCHECK);
@@ -8471,6 +8473,7 @@ cmd_omemo_start(ProfWin* window, const char* const command, gchar** args)
             win_println((ProfWin*)mucwin, THEME_DEFAULT, "!", "Initiating OMEMO session in %s...", mucwin->roomjid);
             omemo_start_muc_sessions(mucwin->roomjid);
             mucwin->is_omemo = TRUE;
+            win_clear_warned_jids((ProfWin*)mucwin);
         } else {
             win_println(window, THEME_DEFAULT, "!", "MUC must be non-anonymous (i.e. be configured to present real jid to anyone) and members-only in order to support OMEMO.");
         }
@@ -8589,6 +8592,7 @@ cmd_omemo_end(ProfWin* window, const char* const command, gchar** args)
 
         chatwin->is_omemo = FALSE;
         accounts_add_omemo_state(session_get_account_name(), chatwin->barejid, FALSE);
+        win_clear_warned_jids((ProfWin*)chatwin);
     } else if (window->type == WIN_MUC) {
         ProfMucWin* mucwin = (ProfMucWin*)window;
         assert(mucwin->memcheck == PROFMUCWIN_MEMCHECK);
@@ -8600,6 +8604,7 @@ cmd_omemo_end(ProfWin* window, const char* const command, gchar** args)
 
         mucwin->is_omemo = FALSE;
         accounts_add_omemo_state(session_get_account_name(), mucwin->roomjid, FALSE);
+        win_clear_warned_jids((ProfWin*)mucwin);
     } else {
         win_println(window, THEME_DEFAULT, "-", "You must be in a regular chat window to start an OMEMO session.");
         return TRUE;

src/omemo/omemo.c

@@ -30,6 +30,7 @@
 #include "omemo/omemo.h"
 #include "omemo/store.h"
 #include "ui/ui.h"
+#include "ui/window.h"
 #include "ui/window_list.h"
 #include "xmpp/connection.h"
 #include "xmpp/muc.h"
@@ -822,7 +823,11 @@ omemo_on_message_send(ProfWin* win, const char* const message, gboolean request_
         recipient_device_id = g_hash_table_lookup(omemo_ctx.device_list, recipients_iter->data);
         if (!recipient_device_id) {
             log_warning("[OMEMO][SEND] cannot find device ids for %s", recipients_iter->data);
-            win_println(win, THEME_ERROR, "!", "Can't find a OMEMO device id for %s.\n", recipients_iter->data);
+
+            if (win_warn_needed(win, "omemo_no_device", recipients_iter->data)) {
+                win_println(win, THEME_ERROR, "!", "Can't find a OMEMO device id for %s.", recipients_iter->data);
+                win_warn_sent(win, "omemo_no_device", recipients_iter->data);
+            }
             continue;
         }
 

src/ui/win_types.h

@@ -133,6 +133,7 @@ typedef struct prof_win_t
     ProfLayout* layout;
     Autocomplete urls_ac;
     Autocomplete quotes_ac;
+    GHashTable* warned_jids;
 } ProfWin;
 
 typedef struct prof_console_win_t

src/ui/window.c

@@ -557,6 +557,10 @@ win_free(ProfWin* window)
     }
     free(window->layout);
 
+    if (window->warned_jids) {
+        g_hash_table_destroy(window->warned_jids);
+    }
+
     switch (window->type) {
     case WIN_CHAT:
     {
@@ -609,6 +613,44 @@ win_free(ProfWin* window)
     free(window);
 }
 
+gboolean
+win_warn_needed(ProfWin* window, const char* const type, const char* const jid)
+{
+    if (!window || !type || !jid) {
+        return TRUE;
+    }
+
+    if (!window->warned_jids) {
+        return TRUE;
+    }
+
+    auto_gchar gchar* key = g_strdup_printf("%s:%s", type, jid);
+    return !g_hash_table_contains(window->warned_jids, key);
+}
+
+void
+win_warn_sent(ProfWin* window, const char* const type, const char* const jid)
+{
+    if (!window || !type || !jid) {
+        return;
+    }
+
+    if (!window->warned_jids) {
+        window->warned_jids = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, NULL);
+    }
+
+    gchar* key = g_strdup_printf("%s:%s", type, jid);
+    g_hash_table_insert(window->warned_jids, key, GINT_TO_POINTER(1));
+}
+
+void
+win_clear_warned_jids(ProfWin* window)
+{
+    if (window && window->warned_jids) {
+        g_hash_table_remove_all(window->warned_jids);
+    }
+}
+
 void
 win_page_up(ProfWin* window, int scroll_size)
 {

src/ui/window.h

@@ -59,6 +59,10 @@ void win_update_entry_message(ProfWin* window, const char* const id, const char*
 
 gboolean win_has_active_subwin(ProfWin* window);
 
+gboolean win_warn_needed(ProfWin* window, const char* const type, const char* const jid);
+void win_warn_sent(ProfWin* window, const char* const type, const char* const jid);
+void win_clear_warned_jids(ProfWin* window);
+
 void win_page_up(ProfWin* window, int scroll_size);
 void win_page_down(ProfWin* window, int scroll_size);
 void win_sub_page_down(ProfWin* window);