fix: preserve custom TUN fields and sync service provider caches

Limit GUI authority to saved TUN fields while preserving custom overrides.

Sync provider caches after service startup, reloads and updates.
Publish copies atomically with session, runtime and cache metadata checks.

src-tauri/src/core/manager/config.rs

@@ -345,6 +345,7 @@ impl CoreManager {
             ConfigApplication::ReloadFrom(staged) => match self.reload_config(&staged).await {
                 Ok(()) => {
                     tracing::Span::current().record("outcome", "staged");
+                    crate::core::service::request_runtime_provider_sync(timing::RUNTIME_PROVIDER_SYNC_DELAY);
                     return Ok(());
                 }
                 Err(err) => logging!(

src-tauri/src/core/manager/state.rs

@@ -276,6 +276,7 @@ impl CoreManager {
                         self.mark_core_ready();
                         self.core_started(RunningMode::Service);
                         self.restore_selected_nodes().await;
+                        service::request_runtime_provider_sync(crate::constants::timing::RUNTIME_PROVIDER_SYNC_DELAY);
                         return Ok(());
                     }
                     Err(e) => {
@@ -300,6 +301,7 @@ impl CoreManager {
             self.mark_core_ready();
             self.core_started(RunningMode::Service);
             self.restore_selected_nodes().await;
+            service::request_runtime_provider_sync(crate::constants::timing::RUNTIME_PROVIDER_SYNC_DELAY);
             Ok(())
         }
     }