Restyle htmleditor.page to match site theme, remove email disconnect button

htmleditor.page previously used hardcoded blue/gray Windows-95-era
inline styles (#678, #abc, #808080, #def) totally disconnected from
the site current dark/gold Bond theme (main.css --bond-* variables) -
this is what showed up as "the old page with the blue stylesheet"
when opening a file to edit. Restyled the window chrome, toolbar,
title bar, and buttons to use the same custom properties/.button
class the rest of the site uses; left the #mainpage content-preview
canvas white since it renders the actual page being edited.

email.js: removed the Disconnect button/handler and its unused icon
from the email toolbar per request. Bumped its cache-buster in
admin-email.subpage.

jetc/barant-site/assets/images/email.js

@@ -24,12 +24,6 @@
       '<path d="M20 11a8 8 0 0 0-14.6-4.4M4 4v5h5"/>' +
       '<path d="M4 13a8 8 0 0 0 14.6 4.4M20 20v-5h-5"/>' +
       '</svg>',
-    disconnect:
-      '<svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round">' +
-      '<path d="M9 21H5a2 2 0 0 1-2-2V5a2 2 0 0 1 2-2h4"/>' +
-      '<path d="M16 17l5-5-5-5"/>' +
-      '<path d="M21 12H9"/>' +
-      '</svg>',
     flag:
       '<svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round">' +
       '<path d="M5 3v18"/>' +
@@ -142,7 +136,6 @@
       '</span>' +
       '<button type="button" id="email-compose-btn" class="icon-btn" title="New Mail">' + ICONS.compose + '</button>' +
       '<button type="button" id="email-refresh-btn" class="icon-btn" title="Refresh">' + ICONS.refresh + '</button>' +
-      '<button type="button" id="email-disconnect-btn" class="icon-btn" title="Disconnect">' + ICONS.disconnect + '</button>' +
       '</span>' +
       '</div>' +
       '<div id="email-layout">' +
@@ -202,23 +195,6 @@
     document.getElementById('email-refresh-btn').addEventListener('click', function() {
       loadMessageList();
     });
-    document.getElementById('email-disconnect-btn').addEventListener('click', function() {
-      // Disconnecting only ever drops the ACTIVE account now (see
-      // /email/disconnect's own doc comment in email.jet) - if another
-      // already-connected account remains, res.active names it and the
-      // view just switches there instead of falling back to the
-      // connect form.
-      post('/email/disconnect', {}).then(function(res) {
-        if (res.active) {
-          resetViewForActiveAccount(res.active);
-        } else {
-          currentFolder = 'Inbox';
-          currentUid = null;
-          syncActiveFolder();
-          showConnectForm();
-        }
-      });
-    });
 
     // Matches sender, subject, or body content in whatever folder is
     // currently open (see __imap.cpp's searchMessages()) - an empty