fix(ui): a described session tab shows just the description (#232)

Reported by @mtiller.

A session named `w2-foo-bar: some description` rendered both halves on the tab, so
the generated id ate the width that the part the user actually chose needed. The
tab now shows the description alone and the `w<n>-<case>` id moves to the tooltip,
where it stays available without being read every time. It is still shown in the
session settings modal. Undescribed tabs are unchanged.

`aria-label` deliberately keeps the FULL name, so screen readers still get the id.

Also fixes a re-render loop this exposed: the incremental update compared
`nameEl.textContent` against the full name, which for a described tab never
matched, so those tabs re-rendered on every pass. The compare now targets the
display label.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/web/public/styles.css

@@ -1383,15 +1383,6 @@ html[data-line-anim="packet"] .connection-line.line-enter {
   text-overflow: ellipsis;
 }
 
-.session-tab .tab-prefix {
-  color: var(--text-muted);
-}
-
-.session-tab .tab-suffix {
-  color: var(--text);
-  font-weight: 500;
-}
-
 /* Tab folder path — hidden by default, shown via .tabs-show-folder on container */
 .session-tab .tab-folder {
   font-size: 0.6rem;