perf: memoize per-frame render hot paths (console, transactions, recent lists)

Immediate-mode render functions re-run every frame; these rebuilt O(N)
state each time even when nothing changed. From a 6-lens perf audit, each
finding verified on a hot-path basis:

- Console: ConsoleModel gains revision(); the full-model filter scan and the
  glyph-by-glyph text-layout pass (BuildConsoleLayout) rebuild only when the
  model / filter / wrap-width / zoom change — previously it re-shaped up to
  10,000 lines every frame even when idle/scrolled. clear() force-invalidates
  the memo mid-render (no OOB on the just-emptied visible set).
- Transactions: the summary-card totals memoize behind the tab's existing
  FNV-1a fingerprint (also folds away a now-duplicate O(N) display-key pass).
- Send / Receive recent lists: early-exit the prefix scan (state.transactions
  is kept newest-first) instead of filtering the whole tx history every frame.
- network_refresh_service: O(new x total) txid find-and-replace -> hash map.
- Sidebar unconfirmed-tx badge cached on last_tx_update + tx count; the
  daemon-memory probe (/proc scan on Linux, popen on macOS) throttled to ~1.5s.

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

src/services/network_refresh_service.cpp

@@ -1108,6 +1108,22 @@ NetworkRefreshService::TransactionRefreshResult NetworkRefreshService::collectRe
         ? &hushChatReceivedOutputs
         : nullptr;
 
+    // Index result.transactions by (txid, type) once so the two replace-loops below
+    // can find-and-replace in O(1) instead of a nested linear scan over the full
+    // (potentially thousands-large) tx list on every 'recent' refresh cycle. The map
+    // holds the index of the FIRST occurrence of each key (preserving the linear
+    // scan's break-on-first-match), and is kept in sync on every append so a later
+    // entry in the same cycle still finds an earlier appended one — exactly as the
+    // re-scanned vector did before.
+    auto txKey = [](const TransactionInfo& tx) {
+        return tx.txid + '\x1f' + tx.type;
+    };
+    std::unordered_map<std::string, std::size_t> byKey;
+    byKey.reserve(result.transactions.size());
+    for (std::size_t i = 0; i < result.transactions.size(); ++i) {
+        byKey.emplace(txKey(result.transactions[i]), i);  // keep first-occurrence index
+    }
+
     try {
         std::set<std::string> recentTxids;
         std::vector<TransactionInfo> recentTransactions;
@@ -1115,15 +1131,13 @@ NetworkRefreshService::TransactionRefreshResult NetworkRefreshService::collectRe
         appendTransparentTransactions(recentTransactions, recentTxids, transactions, snapshot.miningAddresses);
 
         for (auto& recent : recentTransactions) {
-            bool replaced = false;
-            for (auto& existing : result.transactions) {
-                if (existing.txid == recent.txid && existing.type == recent.type) {
-                    existing = recent;
-                    replaced = true;
-                    break;
-                }
+            auto it = byKey.find(txKey(recent));
+            if (it != byKey.end()) {
+                result.transactions[it->second] = recent;
+            } else {
+                byKey.emplace(txKey(recent), result.transactions.size());
+                result.transactions.push_back(std::move(recent));
             }
-            if (!replaced) result.transactions.push_back(std::move(recent));
         }
     } catch (const std::exception& e) {
         DEBUG_LOGF("recent listtransactions error: %s\n", e.what());
@@ -1149,15 +1163,13 @@ NetworkRefreshService::TransactionRefreshResult NetworkRefreshService::collectRe
                                                snapshot.miningAddresses,
                                                hushChatReceivedOutputsPtr);
             for (auto& scanned : scannedTransactions) {
-                bool replaced = false;
-                for (auto& existing : result.transactions) {
-                    if (existing.txid == scanned.txid && existing.type == scanned.type) {
-                        existing = scanned;
-                        replaced = true;
-                        break;
-                    }
+                auto it = byKey.find(txKey(scanned));
+                if (it != byKey.end()) {
+                    result.transactions[it->second] = scanned;
+                } else {
+                    byKey.emplace(txKey(scanned), result.transactions.size());
+                    result.transactions.push_back(std::move(scanned));
                 }
-                if (!replaced) result.transactions.push_back(std::move(scanned));
             }
             if (currentBlockHeight >= 0) result.shieldedScanHeights[address] = currentBlockHeight;
             ++result.shieldedAddressesScanned;