Add global music player, invoicing/payment system, account subpages, mail account admin, and the qualityiron.vegas Jet 2.0 port

Jet interpreter (Tag.cpp, __call.cpp, __imap*.cpp/h, __smtpsend.cpp/h,
__imapemptyfolder.cpp/h - new): assorted parser/tag fixes found across
this work - a stray literal-tag-in-comment and backslash-quote parser
corruption class, a dangling-pointer fix, a __call.cpp fd leak, IMAP
folder-management tags, multi-account/per-host IMAP support, and a
smtpsend Message-ID fix.

barant.com site (jetc/barant-site/):
- A site-wide persistent music player (header band, playlist/queue,
  stereo FFT EQ, session-persisted state) fed by new library/
  ianslibrary/music song-list subpages.
- /account split into info/phones/invoices subpages; a full invoicing
  and Square payment system (create/edit/copy/pay/email invoice);
  admin invoice management and mail-account management subpages.
- /services split into overview/hosting/siptrunking/documents
  subpages, retiring the old standalone pages.
- SIPPHONE.tag: a Jet 2.0 WebRTC softphone tag.
- main.css/spa.js/email.js: the SPA loading indicator, the music
  player band styling, and assorted fixes accumulated alongside this
  work.

qualityiron-site/: the qualityiron.vegas job/contractor/customer/
document management app, ported from its original Jet 1.4 codebase to
Jet 2.0 as barant.coms APIServers second multi-tenant site.

wcwc/wcwc.jet: the WCWC site Jet source (wcwc.jtc build output not
included).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

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

@@ -1,6 +1,7 @@
 (function() {
   var content = document.getElementById('content');
   var form = document.getElementById('mainform');
+  var loadingIndicator = document.getElementById('spa-loading-indicator');
   // Lives outside #content (a sibling in the persistent shell, next to
   // the menu bar/form) - a fragment swap never touches it on its own,
   // so a per-page side menu would otherwise stay frozen on whichever
@@ -220,6 +221,12 @@
   function navigate(url, push) {
     var sep = url.indexOf('?') === -1 ? '?' : '&';
     content.classList.add('spa-fading');
+    // Opacity transition alone (see the CSS) means a fetch that resolves
+    // quickly never gets the indicator past a barely-visible opacity
+    // before this removes the class again - exactly the "do not flash
+    // this for a fast load" behavior wanted, with no separate delay
+    // timer needed to achieve it.
+    if (loadingIndicator) loadingIndicator.classList.add('spa-loading-visible');
     Promise.all([
       fetch(url + sep + '_fragment=1', { credentials: 'same-origin' }).then(function(r) { return r.text(); }),
       delay(180)
@@ -233,6 +240,7 @@
           syncActiveTab(finalUrl.split('?')[0]);
         }
         content.classList.remove('spa-fading');
+        if (loadingIndicator) loadingIndicator.classList.remove('spa-loading-visible');
       });
   }
 
@@ -254,6 +262,7 @@
       var subpage = fd.get('SUBPAGE') || '';
       var url = formPrefix + '/' + page + (subpage ? '/' + subpage : '');
       content.classList.add('spa-fading');
+      if (loadingIndicator) loadingIndicator.classList.add('spa-loading-visible');
       Promise.all([
         fetch(url + '?_fragment=1', {
           method: 'POST',
@@ -271,6 +280,7 @@
             syncActiveTab(finalUrl.split('?')[0]);
           }
           content.classList.remove('spa-fading');
+          if (loadingIndicator) loadingIndicator.classList.remove('spa-loading-visible');
         });
     });
   }
@@ -279,6 +289,24 @@
     navigate(window.location.pathname + window.location.search, false);
   });
 
+  // Instant visual feedback on a side-menu click - without this, the
+  // active-item highlight only updated once applyResponse() swapped in
+  // the new #_spa_panelmenu markup after the fetch finished, which read
+  // as unresponsive (the click did nothing visible until the whole
+  // subpage had already loaded). That server-rendered swap is still the
+  // authoritative source of truth and will correct this on arrival (e.g.
+  // if a click ends up redirected somewhere else entirely), so this is
+  // purely an optimistic bridge, not a second source of truth.
+  if (panelMenu) {
+    panelMenu.addEventListener('click', function(e) {
+      var a = e.target.closest('a');
+      if (!a || !panelMenu.contains(a)) return;
+      var current = panelMenu.querySelector('.submenuitem-active');
+      if (current) current.classList.remove('submenuitem-active');
+      a.classList.add('submenuitem-active');
+    });
+  }
+
   // Drag-to-resize for the side menu (#panelmenu) against the main
   // content column - the resizer bar (#panelmenu-resizer) lives in the
   // persistent shell right alongside panelMenu itself (see its own