refine(daemon-update): taller card, unified info surface, tactile card polish

Design pass on the two-pane node updater:
- Taller card (a generous share of the window) so release notes get vertical
  room and usually don't need to scroll.
- Wrap the version header + release notes in ONE rounded Material surface (drop
  the divider between them); the notes markdown gets inner padding so it doesn't
  touch the edges, and the header stays pinned while long notes scroll within.
- The verify note + install button now sit OUTSIDE that surface; the install
  button is sized to its text instead of full width.
- Version cards: slightly smaller radius, accent bar removed, and the currently
  installed (active) node is marked with a check on the right of its card.
- Footer: dropped the divider above Close and enlarged the Close button.

Verified 100% + 150%, dark + light.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/util/i18n.cpp

@@ -1488,6 +1488,7 @@ void I18n::loadBuiltinEnglish()
         strings_["daemon_update_released"]         = "Released:";
         strings_["daemon_update_no_notes"]         = "No release notes for this version.";
         strings_["daemon_update_install_this"]     = "Install this version";
+        strings_["daemon_update_active_tt"]        = "The currently installed (active) node";
 
         // --- Lite Network tab (server browser) ---
         strings_["lite_net_title"]        = "Lite Servers";