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/app.cpp

@@ -28,6 +28,7 @@
 #include "ui/windows/transactions_tab.h"
 #include "ui/windows/mining_tab.h"
 #include "ui/windows/peers_tab.h"
+#include "ui/windows/network_tab.h"
 #include "ui/windows/explorer_tab.h"
 #include "ui/windows/market_tab.h"
 #include "ui/windows/settings_window.h"
@@ -429,14 +430,18 @@ wallet::LiteRolloutDecision resolveLiteRolloutDecision(config::Settings& setting
 }
 } // namespace
 
-void App::rebuildLiteWallet()
+void App::rebuildLiteWallet(bool force)
 {
     if (!supportsLiteBackend() || !settings_) return;
-    // Don't tear down a live session: if a wallet is already open (and possibly mid-sync), the
-    // new server selection is already persisted to settings and will take effect the next time
-    // the controller is built (next launch, or before another wallet is opened). Rebuilding now
-    // would discard the open wallet and its in-flight, uninterruptible sync.
-    if (lite_wallet_ && lite_wallet_->walletOpen()) return;
+    // Don't tear down a live session unless forced: if a wallet is already open (and possibly
+    // mid-sync), the new server selection is already persisted to settings and will take effect
+    // the next time the controller is built (next launch, or before another wallet is opened).
+    // Rebuilding would discard the open wallet and its in-flight, uninterruptible sync — which is
+    // exactly what the Network tab's apply-immediately server switch wants (force=true). Replacing
+    // lite_wallet_ destroys the old controller; its destructor detaches the uninterruptible sync
+    // thread (which keeps the shared bridge alive) and only joins the short poll worker, so this
+    // does not block. The app's auto-open loop then reopens the wallet against the new server.
+    if (!force && lite_wallet_ && lite_wallet_->walletOpen()) return;
 
     lite_wallet_ = wallet::LiteWalletController::createLinked(
         walletCapabilities(),
@@ -1318,6 +1323,9 @@ void App::render()
         case ui::NavPage::Peers:
             ui::RenderPeersTab(this);
             break;
+        case ui::NavPage::LiteNetwork:
+            ui::RenderLiteNetworkTab(this);
+            break;
         case ui::NavPage::Explorer:
             ui::RenderExplorerTab(this);
             break;