feat(lite): ObsidianDragonLite Network tab — server browser

A lite-wallet-only "Network" tab (full-node keeps the Peers tab; exactly one shows per variant)
to manage lightwalletd servers, replacing the basic selector that was in Settings.

- Card list of servers with per-server latency + status dot, DNS host + resolved IP, and an
  Official/Custom pill. Official DragonX servers get a glowing outline.
- Pick a server (Sticky) by clicking its card, or toggle "use a random server" (Random mode);
  selection applies immediately (App::rebuildLiteWallet(force=true) tears down + rebuilds the
  controller against the new server and resyncs — its dtor detaches the uninterruptible sync
  thread, so this doesn't block).
- Add custom servers; hide/unhide servers (persisted set, revealed by a "Show hidden" toggle).
- Latency/IP come from a new background probe (util/LiteServerProbe): libcurl CONNECT_ONLY does
  the TCP+TLS handshake (works for gRPC lightwalletd, no HTTP response needed), recording
  APPCONNECT_TIME as latency and CURLINFO_PRIMARY_IP. Auto-runs on tab open + a Refresh button.

Wiring: WalletUiSurface::LiteNetwork (gated !fullNodePagesAvailable) + NavPage::LiteNetwork in
the sidebar + app.cpp dispatch; settings gains a hidden-servers set; isOfficialLiteServer() added
to lite_connection_service. The Settings page lite-server selector + its plumbing are removed
(single source of truth = the tab).

Reuses the existing server model (LiteServerPreference, Sticky/Random, selectLiteServer) and UI
primitives (DrawGlassPanel, ThemeEffects glow, peers-tab ping-dot idiom). Unit-tested
(liteServerHost, isOfficialLiteServer) + an env-gated live probe (verified vs lite.dragonx.is:
online, latency, IP). Both variants + lite-backend build; suite passes; hygiene clean; GUI
smoke-launched without crash.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/ui/sidebar.h

@@ -31,6 +31,7 @@ enum class NavPage {
     // --- separator ---
     Console,
     Peers,
+    LiteNetwork,   // lite-only "Network" tab (full-node uses Peers); exactly one shows per variant
     Explorer,
     Settings,
     Count_
@@ -52,7 +53,8 @@ inline const NavItem kNavItems[] = {
     { "Mining",    NavPage::Mining,   "TOOLS",   "mining",   "tools"     },
     { "Market",    NavPage::Market,   nullptr,    "market",   nullptr     },
     { "Console",   NavPage::Console,  "ADVANCED","console",  "advanced"  },
-    { "Network",   NavPage::Peers,    nullptr,    "network",  nullptr     },
+    { "Network",   NavPage::Peers,       nullptr, "network",  nullptr     },
+    { "Network",   NavPage::LiteNetwork, nullptr, "network",  nullptr     },
     { "Explorer",  NavPage::Explorer, nullptr,    "explorer", nullptr     },
     { "Settings",  NavPage::Settings, nullptr,    "settings", nullptr     },
 };
@@ -78,6 +80,7 @@ inline wallet::WalletUiSurface NavPageSurface(NavPage page)
     case NavPage::Market:   return wallet::WalletUiSurface::Market;
     case NavPage::Console:  return wallet::WalletUiSurface::Console;
     case NavPage::Peers:    return wallet::WalletUiSurface::Peers;
+    case NavPage::LiteNetwork: return wallet::WalletUiSurface::LiteNetwork;
     case NavPage::Explorer: return wallet::WalletUiSurface::Explorer;
     case NavPage::Settings: return wallet::WalletUiSurface::Settings;
     default:                return wallet::WalletUiSurface::Overview;
@@ -101,6 +104,7 @@ inline const char* GetNavIconMD(NavPage page)
     case NavPage::Market:    return ICON_MD_TRENDING_UP;
     case NavPage::Console:   return ICON_MD_TERMINAL;
     case NavPage::Peers:     return ICON_MD_HUB;
+    case NavPage::LiteNetwork: return ICON_MD_HUB;
     case NavPage::Explorer:  return ICON_MD_EXPLORE;
     case NavPage::Settings:  return ICON_MD_SETTINGS;
     default:                 return ICON_MD_HOME;