Second pass: four dialogs that were never wrapped

A sweep for UI text still rendering in English, after the nine catalogues were
brought up to date. Four dialogs were building their own English:

  - The delete confirmation in MailView, entirely: both titles, both messages
    and the confirm label. Its counts read "message(s)", which is a
    parenthesis standing in for agreement -- every language that inflects got
    the wrong form. They are plural() calls now.
  - Rename, in the Files tree.
  - New address book, and its Name placeholder.
  - New category, and its Name placeholder. The button opening that dialog was
    already translated, which is how it went unnoticed: the label read right
    and the dialog it opened did not.

Rename, New address book, New category, Name and Delete are already in all
nine catalogues. Delete?, Delete forever? and the two plural forms are new and
land with each language.

Verified: typecheck clean, 1000 tests pass.

web/src/views/files/FilesTree.tsx

@@ -257,7 +257,7 @@ export function FilesTree() {
               label={t("Rename")}
               disabled={!menuNode.myRights?.mayRename}
               onClick={async () => {
-                const name = await promptDialog({ title: "Rename", defaultValue: menuNode.name });
+                const name = await promptDialog({ title: t("Rename"), defaultValue: menuNode.name });
                 if (!name?.trim() || name === menuNode.name) return;
                 try {
                   await useFiles.getState().rename(menuNode.id, name.trim());