chore(web): drop probe button and footer rail

The 15 s health poll stays; the manual trigger and the rtt/poll-note
footer earned nothing over it.

Closes #106

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

web/src/style.css

@@ -134,14 +134,6 @@ body {
   box-shadow: inset 0 1px var(--highlight);
 }
 
-.rail-foot {
-  margin-top: auto;
-  border-bottom: 0;
-  border-top: 1px solid var(--line);
-  justify-content: space-between;
-  font-size: var(--text-xs);
-}
-
 .rail-id {
   display: flex;
   align-items: center;