feat(lite): add lite6 + lite7 to the default lite-wallet server list

Ship https://lite6.dragonx.is and https://lite7.dragonx.is as default
lightwalletd servers in both the Settings defaults and the connection-service
fallback list. Existing installs (whose saved server list predates these)
pick them up via a load-time merge that appends any missing default server —
safe because servers are hidden, never deleted, so a removed server isn't
resurrected. Consolidates the Settings default list into a single
Settings::defaultLiteServers() source of truth.

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

src/config/settings.cpp

@@ -108,6 +108,20 @@ void loadClamped(const json& j, const char* key, T& field, T lo, T hi)
 
 } // namespace
 
+std::vector<Settings::LiteServerPreference> Settings::defaultLiteServers()
+{
+    return {
+        {"https://lite.dragonx.is", "DragonX Lite", true},
+        {"https://lite1.dragonx.is", "DragonX Lite 1", true},
+        {"https://lite2.dragonx.is", "DragonX Lite 2", true},
+        {"https://lite3.dragonx.is", "DragonX Lite 3", true},
+        {"https://lite4.dragonx.is", "DragonX Lite 4", true},
+        {"https://lite5.dragonx.is", "DragonX Lite 5", true},
+        {"https://lite6.dragonx.is", "DragonX Lite 6", true},
+        {"https://lite7.dragonx.is", "DragonX Lite 7", true}
+    };
+}
+
 std::string Settings::getDefaultPath()
 {
     // Single per-platform, per-variant config dir (util::Platform::getConfigDir handles the
@@ -307,6 +321,16 @@ bool Settings::load(const std::string& path)
                     }
                     lite_servers_.push_back(preference);
                 }
+                // Surface newly-shipped default servers (e.g. lite6/lite7) on an existing
+                // install whose saved list predates them. Servers are hidden (see
+                // lite_hidden_servers_), never deleted, so appending a missing default won't
+                // resurrect one the user intentionally removed.
+                for (const auto& def : defaultLiteServers()) {
+                    bool present = false;
+                    for (const auto& s : lite_servers_)
+                        if (s.url == def.url) { present = true; break; }
+                    if (!present) lite_servers_.push_back(def);
+                }
             }
             if (lite.contains("rollout_override") && lite["rollout_override"].is_string()) {
                 const auto v = lite["rollout_override"].get<std::string>();