feat(wallet): persist history and surface pending sends

Add an encrypted SQLite transaction history cache with cached tip metadata and
per-address shielded scan progress so startup and full refreshes avoid
re-scanning every z-address while still invalidating on wallet/address/rescan
changes.

Improve wallet history loading by paging transparent transactions, preserving
cached shielded and sent rows, keeping recent/unconfirmed activity visible, and
classifying mining-address receives. Show z_sendmany opid sends immediately in
History and Overview, pin pending rows through refreshes, and apply optimistic
address/balance debits until opids resolve.

Add timestamped RPC console tracing by source/method without logging params or
results, reduce redundant refresh/RPC calls, and cache Explorer recent block
summaries in SQLite.

Expand focused tests for transaction cache encryption, scan-progress
persistence/invalidation, history preservation, operation-status parsing,
pending send visibility, and Explorer/RPC refresh behavior.

src/ui/windows/shield_dialog.cpp

@@ -185,6 +185,7 @@ void ShieldDialog::render(App* app)
                         nlohmann::json result;
                         std::string error;
                         try {
+                            rpc::RPCClient::TraceScope trace("Send tab / Shield coinbase");
                             result = rpc->call("z_shieldcoinbase", {from, to, fee, limit});
                         } catch (const std::exception& e) {
                             error = e.what();
@@ -215,6 +216,7 @@ void ShieldDialog::render(App* app)
                         nlohmann::json result;
                         std::string error;
                         try {
+                            rpc::RPCClient::TraceScope trace("Send tab / Merge funds");
                             result = rpc->call("z_mergetoaddress", {addrs, to, fee, 0, limit});
                         } catch (const std::exception& e) {
                             error = e.what();
@@ -258,6 +260,7 @@ void ShieldDialog::render(App* app)
                         nlohmann::json result;
                         std::string error;
                         try {
+                            rpc::RPCClient::TraceScope trace("Send tab / Shield operation status");
                             nlohmann::json ids = nlohmann::json::array();
                             ids.push_back(opid);
                             result = rpc->call("z_getoperationstatus", {ids});