perf(node): throttle RPC polling during sync so block download isn't slowed

The full-node wallet polled the daemon at the per-tab cadence regardless of sync state.
On the Peers/Network tab that meant getpeerinfo every 5s + core every 5s + a full
transaction scan on every new block — and blocks arrive fast during sync. Each of those
calls takes the daemon's cs_main lock, the same lock block connection needs, so the node
synced noticeably slower than on the lightweight Console tab (core 10s, no peer polling).

Make the refresh cadence sync-aware:
- RefreshScheduler::kSyncProfile {core 10s, transactions/addresses/peers disabled} is applied
  to ALL tabs while state_.sync.syncing, and reverts to the per-tab profile when sync ends.
  applyRefreshPolicy() picks the profile; update() re-applies it on the syncing<->synced
  transition. This suppresses getpeerinfo and the per-block tx scan during sync (that data is
  incomplete mid-sync anyway) — every tab now syncs as fast as Console.
- collectCoreRefreshResult(rpc, includeBalance): skip z_gettotalbalance (wallet lock + cs_main)
  while syncing; only getblockchaininfo runs, which is also what drives sync-progress detection.
  applyCoreRefreshResult already leaves the balance untouched when balanceOk is false.

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

src/services/network_refresh_service.cpp

@@ -284,18 +284,20 @@ NetworkRefreshService::CoreRefreshResult NetworkRefreshService::parseCoreRefresh
     return result;
 }
 
-NetworkRefreshService::CoreRefreshResult NetworkRefreshService::collectCoreRefreshResult(RefreshRpcGateway& rpc)
+NetworkRefreshService::CoreRefreshResult NetworkRefreshService::collectCoreRefreshResult(RefreshRpcGateway& rpc, bool includeBalance)
 {
     json totalBalance;
     json blockInfo;
     bool balanceOk = false;
     bool blockOk = false;
 
-    try {
-        totalBalance = rpc.call("z_gettotalbalance", json::array());
-        balanceOk = true;
-    } catch (const std::exception& e) {
-        DEBUG_LOGF("Balance error: %s\n", e.what());
+    if (includeBalance) {
+        try {
+            totalBalance = rpc.call("z_gettotalbalance", json::array());
+            balanceOk = true;
+        } catch (const std::exception& e) {
+            DEBUG_LOGF("Balance error: %s\n", e.what());
+        }
     }
 
     try {

src/services/network_refresh_service.h

@@ -230,7 +230,10 @@ public:
                                                     bool balanceOk,
                                                     const nlohmann::json& blockInfo,
                                                     bool blockOk);
-    static CoreRefreshResult collectCoreRefreshResult(RefreshRpcGateway& rpc);
+    // includeBalance=false skips z_gettotalbalance (which takes the wallet lock + cs_main) and only
+    // fetches getblockchaininfo — used while syncing, where the balance is incomplete anyway and the
+    // wallet should minimise lock contention with block connection.
+    static CoreRefreshResult collectCoreRefreshResult(RefreshRpcGateway& rpc, bool includeBalance = true);
     static MiningRefreshResult parseMiningRefreshResult(const nlohmann::json& miningInfo,
                                                         bool miningOk,
                                                         const nlohmann::json& localHashrate,

src/services/refresh_scheduler.h

@@ -34,6 +34,14 @@ public:
     static constexpr float kTxMaxAge = 15.0f;
     static constexpr float kOpidPoll = 2.0f;
 
+    // Low-impact polling profile applied while the daemon is SYNCING, regardless of the active tab.
+    // Only a slow progress poll runs (core, 10s); transactions/addresses/peers are disabled (0).
+    // Frequent getpeerinfo, per-block transaction scans, and balance polls all contend for the
+    // daemon's cs_main lock and measurably slow block connection during sync — this is exactly why
+    // the lightweight Console tab syncs faster than the Peers tab. Reverts to the per-tab profile
+    // once sync completes. (Tx/address/balance data is incomplete mid-sync anyway.)
+    static constexpr Intervals kSyncProfile{10.0f, 0.0f, 0.0f, 0.0f};
+
     static Intervals intervalsForPage(ui::NavPage page);
 
     void applyPage(ui::NavPage page);