fix: set timing bar widths via JS DOM assignment after innerHTML

All previous attempts (inline style=, CSS custom property via style=)
were ineffective. Setting element.style.width directly in JS after
panel.innerHTML is assigned is the only approach that cannot be
interfered with by CSP or attribute sanitisation.

Width is stored as data-w attribute in the HTML string and applied
by querySelectorAll('.timing-bar[data-w]') post-render.

public/style.css

@@ -952,7 +952,6 @@ body {
 
 .timing-bar {
   height: 100%;
-  width: var(--bar-w, 100%);
   background: var(--accent);
   border-radius: 4px;
   min-width: 2px;