core: add /theme rename to rename a user theme file

doc/de/weechat_user.de.adoc

@@ -2283,6 +2283,19 @@ Reserved names (built-in theme names like `+light+` and any name
 starting with `+backup-+`) are refused. Files live at
 `+${weechat_config_dir}/themes/<name>.theme+`.
 
+Rename a user theme (typical use: keep a useful automatic backup
+under a meaningful name):
+
+----
+/theme rename backup-20260525-094210-123456 mybackup
+----
+
+Built-in themes have no file and cannot be renamed; the target name
+cannot match a built-in name or start with `+backup-+`, and the
+target file must not already exist. The `+[info]+` `+name+` field
+inside the file is rewritten so `/theme info` reports the new name
+consistently.
+
 Delete a user theme:
 
 ----

doc/en/weechat_user.en.adoc

@@ -2270,6 +2270,19 @@ Reserved names (built-in theme names like `+light+` and any name
 starting with `+backup-+`) are refused. Files live at
 `+${weechat_config_dir}/themes/<name>.theme+`.
 
+Rename a user theme (typical use: keep a useful automatic backup
+under a meaningful name):
+
+----
+/theme rename backup-20260525-094210-123456 mybackup
+----
+
+Built-in themes have no file and cannot be renamed; the target name
+cannot match a built-in name or start with `+backup-+`, and the
+target file must not already exist. The `+[info]+` `+name+` field
+inside the file is rewritten so `/theme info` reports the new name
+consistently.
+
 Delete a user theme:
 
 ----

doc/fr/weechat_user.fr.adoc

@@ -2319,6 +2319,20 @@ Les noms réservés (noms de thèmes intégrés comme `+light+` et tout nom
 commençant par `+backup-+`) sont refusés. Les fichiers sont placés
 dans `+${weechat_config_dir}/themes/<nom>.theme+`.
 
+Renommer un thème utilisateur (usage typique : conserver une
+sauvegarde automatique utile sous un nom plus parlant) :
+
+----
+/theme rename backup-20260525-094210-123456 maSauvegarde
+----
+
+Les thèmes intégrés n'ont pas de fichier et ne peuvent pas être
+renommés ; le nom cible ne peut pas correspondre à un nom intégré ni
+commencer par `+backup-+`, et le fichier cible ne doit pas déjà
+exister. Le champ `+name+` de la section `+[info]+` à l'intérieur du
+fichier est réécrit afin que `/theme info` affiche le nouveau nom de
+manière cohérente.
+
 Supprimer un thème utilisateur :
 
 ----

doc/it/weechat_user.it.adoc

@@ -2525,6 +2525,19 @@ Reserved names (built-in theme names like `+light+` and any name
 starting with `+backup-+`) are refused. Files live at
 `+${weechat_config_dir}/themes/<name>.theme+`.
 
+Rename a user theme (typical use: keep a useful automatic backup
+under a meaningful name):
+
+----
+/theme rename backup-20260525-094210-123456 mybackup
+----
+
+Built-in themes have no file and cannot be renamed; the target name
+cannot match a built-in name or start with `+backup-+`, and the
+target file must not already exist. The `+[info]+` `+name+` field
+inside the file is rewritten so `/theme info` reports the new name
+consistently.
+
 Delete a user theme:
 
 ----

doc/ja/weechat_user.ja.adoc

@@ -2461,6 +2461,19 @@ Reserved names (built-in theme names like `+light+` and any name
 starting with `+backup-+`) are refused. Files live at
 `+${weechat_config_dir}/themes/<name>.theme+`.
 
+Rename a user theme (typical use: keep a useful automatic backup
+under a meaningful name):
+
+----
+/theme rename backup-20260525-094210-123456 mybackup
+----
+
+Built-in themes have no file and cannot be renamed; the target name
+cannot match a built-in name or start with `+backup-+`, and the
+target file must not already exist. The `+[info]+` `+name+` field
+inside the file is rewritten so `/theme info` reports the new name
+consistently.
+
 Delete a user theme:
 
 ----

doc/pl/weechat_user.pl.adoc

@@ -2277,6 +2277,19 @@ Reserved names (built-in theme names like `+light+` and any name
 starting with `+backup-+`) are refused. Files live at
 `+${weechat_config_dir}/themes/<name>.theme+`.
 
+Rename a user theme (typical use: keep a useful automatic backup
+under a meaningful name):
+
+----
+/theme rename backup-20260525-094210-123456 mybackup
+----
+
+Built-in themes have no file and cannot be renamed; the target name
+cannot match a built-in name or start with `+backup-+`, and the
+target file must not already exist. The `+[info]+` `+name+` field
+inside the file is rewritten so `/theme info` reports the new name
+consistently.
+
 Delete a user theme:
 
 ----

doc/sr/weechat_user.sr.adoc

@@ -2179,6 +2179,19 @@ Reserved names (built-in theme names like `+light+` and any name
 starting with `+backup-+`) are refused. Files live at
 `+${weechat_config_dir}/themes/<name>.theme+`.
 
+Rename a user theme (typical use: keep a useful automatic backup
+under a meaningful name):
+
+----
+/theme rename backup-20260525-094210-123456 mybackup
+----
+
+Built-in themes have no file and cannot be renamed; the target name
+cannot match a built-in name or start with `+backup-+`, and the
+target file must not already exist. The `+[info]+` `+name+` field
+inside the file is rewritten so `/theme info` reports the new name
+consistently.
+
 Delete a user theme:
 
 ----