Permissions: a certificates role

A template for tokens and users that get certificates for other hosts
(jarl cert get): certificates:write, to narrow with names= in the web
UI's "Insert a template…", or --role certificates in the CLI. The token
form's template filter no longer counts "*" as covering certificates,
as the server doesn't.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/web/static/assets/pages/users.js

@@ -195,7 +195,8 @@ async function rotateDialog(t, redraw) {
 function coveredBy(user, grant) {
   if (!user || user.admin) return true;
   const [res, acc] = grant.split(/\s+/)[0].split(":");
-  return (user.grants || []).some((g) => (g.resource === "*" || g.resource === res) && (g.access === "write" || acc === "read"));
+  // "*" never covers certificates (they hand out private keys).
+  return (user.grants || []).some((g) => ((g.resource === "*" && res !== "certificates") || g.resource === res) && (g.access === "write" || acc === "read"));
 }
 
 // newTokenForm makes a token for owner (the user it belongs to). Its