refine(daemon-update): pad info surface, right-aligned icon badges, centered install

- Fix the info surface padding: a borderless BeginChild ignores WindowPadding
  unless ImGuiChildFlags_AlwaysUseWindowPadding is set, so the content was
  touching the surface edges. Add the flag + generous padding, and make the
  surface a touch more visible so it reads as a container.
- Version list: replace the inline text badges with a single right-aligned icon
  badge per item — check (installed/active), science flask (pre-release), or
  new-releases (newest available) — each with a tooltip.
- Center the Download & install button (still sized to its text).

Verified 100% + 150%, dark + light.

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

src/util/i18n.cpp

@@ -1489,6 +1489,8 @@ void I18n::loadBuiltinEnglish()
         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";
+        strings_["daemon_update_latest_tt"]        = "Newest available version";
+        strings_["daemon_update_prerelease_tt"]    = "Pre-release / testing build";
 
         // --- Lite Network tab (server browser) ---
         strings_["lite_net_title"]        = "Lite Servers";