feat(ui): link sessions to chat page

- Session names in the Sessions table are now clickable links
- Clicking navigates to /chat?session=<key> with that session loaded
- Global sessions excluded (not real conversations)
- Added .session-link CSS styling (accent color, underline on hover)
- Chat page reads 'session' query param and cleans URL after applying

ui/src/styles/components.css

@@ -454,6 +454,15 @@
   background: rgba(0, 0, 0, 0.2);
 }
 
+.session-link {
+  text-decoration: none;
+  color: var(--accent);
+}
+
+.session-link:hover {
+  text-decoration: underline;
+}
+
 .log-stream {
   border: 1px solid var(--border);
   border-radius: 14px;