fix(forum): correct sidebar nesting and duplicate widget card

- keep .sidebar a sibling of .content-wrap inside main.container so the
  theme's float math puts it in the right column
- move fluid widget zones inside main on plate / post routes
- drop the leftover .forum-home .jio-widget-box override that stacked a
  second card background on the user card
- balance the compose page shell for guests and editors

assets/css/routes/forum.css

@@ -67,9 +67,6 @@
 .hide-type-drop .select-drop-box .badg.active{--this-bg:var(--focus-color);--this-color:#fff}
 .hide-type-drop textarea{margin-top:8px;width:100%}
 .jio-forum__captcha{margin-bottom:15px}
-.forum-home .jio-widget-box{clear:both;background-color:var(--main-bg-color);padding:15px;box-shadow:0 0 10px var(--main-shadow);border-radius:var(--main-radius);margin-bottom:20px}
-.forum-home .jio-widget-box .btn-block{display:block;width:100%;text-align:center}
-.forum-home .jio-widget-box .title-theme{font-size:15px;font-weight:600}
 .quick-posts-form .form-control{width:100%}
 .quick-posts-form select.form-control{width:auto;min-width:140px}
 .quick-posts-form .jio-forum__message:empty{display:none}