fix(pgp): prevent plaintext fallback in PGP/OX encryption

Block all three code paths in message_send_chat_pgp that previously
fell back to sending unencrypted messages: encryption failure, missing
PGP key, and missing LibGPGME. Each path now shows a specific error
in the chat window and returns NULL so the caller skips logging and
display.

Also replace the generic cons_show for OX signcrypt failure with a
win_println on the current window, ensuring the user sees the error
even when the chat window is not focused.

Improve p_gpg_encrypt error reporting by adding a gchar** err
out-parameter. Each failure path now sets a descriptive message
(e.g. missing recipient key, missing sender key, GPGME context
failure, encryption failure) so the caller can display the exact
reason to the user.

Fix a memory leak: gpgme_key_unref(receiver_key) was missing from
the sender_key failure path.

src/pgp/gpg.c

@@ -519,13 +519,15 @@ p_gpg_sign(const gchar* const str, const gchar* const fp)
 }
 
 gchar*
-p_gpg_encrypt(const gchar* const barejid, const gchar* const message, const gchar* const fp)
+p_gpg_encrypt(const gchar* const barejid, const gchar* const message, const gchar* const fp, gchar** err)
 {
     ProfPGPPubKeyId* pubkeyid = g_hash_table_lookup(pubkeys, barejid);
     if (!pubkeyid) {
+        *err = g_strdup("No PGP key found for recipient");
         return NULL;
     }
     if (!pubkeyid->id) {
+        *err = g_strdup("No key ID found for recipient");
         return NULL;
     }
 
@@ -538,6 +540,7 @@ p_gpg_encrypt(const gchar* const barejid, const gchar* const message, const gcha
     gpgme_ctx_t ctx;
     gpgme_error_t error = gpgme_new(&ctx);
     if (error) {
+        *err = g_strdup_printf("Failed to create GPGME context: %s %s", gpgme_strsource(error), gpgme_strerror(error));
         log_error("GPG: Failed to create gpgme context. %s %s", gpgme_strsource(error), gpgme_strerror(error));
         return NULL;
     }
@@ -545,6 +548,7 @@ p_gpg_encrypt(const gchar* const barejid, const gchar* const message, const gcha
     gpgme_key_t receiver_key;
     error = gpgme_get_key(ctx, pubkeyid->id, &receiver_key, 0);
     if (error || receiver_key == NULL) {
+        *err = g_strdup_printf("Failed to get receiver key '%s': %s %s", pubkeyid->id, gpgme_strsource(error), gpgme_strerror(error));
         log_error("GPG: Failed to get receiver_key. %s %s", gpgme_strsource(error), gpgme_strerror(error));
         gpgme_release(ctx);
         return NULL;
@@ -554,8 +558,10 @@ p_gpg_encrypt(const gchar* const barejid, const gchar* const message, const gcha
     gpgme_key_t sender_key = NULL;
     error = gpgme_get_key(ctx, fp, &sender_key, 0);
     if (error || sender_key == NULL) {
+        *err = g_strdup_printf("Failed to get sender key '%s': %s %s", fp, gpgme_strsource(error), gpgme_strerror(error));
         log_error("GPG: Failed to get sender_key. %s %s", gpgme_strsource(error), gpgme_strerror(error));
         gpgme_release(ctx);
+        gpgme_key_unref(receiver_key);
         return NULL;
     }
     keys[1] = sender_key;
@@ -574,7 +580,8 @@ p_gpg_encrypt(const gchar* const barejid, const gchar* const message, const gcha
     gpgme_key_unref(sender_key);
 
     if (error) {
-        log_error("GPG: Failed to encrypt message. %s %s", gpgme_strsource(error), gpgme_strerror(error));
+        *err = g_strdup_printf("Encryption failed: (%s) %s", gpgme_strsource(error), gpgme_strerror(error));
+        log_error("GPG: Failed to encrypt message. (%s) %s", gpgme_strsource(error), gpgme_strerror(error));
         return NULL;
     }
 

src/pgp/gpg.h

@@ -42,7 +42,7 @@ gboolean p_gpg_available(const gchar* const barejid);
 const gchar* p_gpg_libver(void);
 gchar* p_gpg_sign(const gchar* const str, const gchar* const fp);
 void p_gpg_verify(const gchar* const barejid, const gchar* const sign);
-gchar* p_gpg_encrypt(const gchar* const barejid, const gchar* const message, const gchar* const fp);
+gchar* p_gpg_encrypt(const gchar* const barejid, const gchar* const message, const gchar* const fp, gchar** err);
 gchar* p_gpg_decrypt(const gchar* const cipher);
 void p_gpg_free_decrypted(gchar* decrypted);
 gchar* p_gpg_autocomplete_key(const gchar* const search_str, gboolean previous, void* context);