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/app.cpp

@@ -1806,7 +1806,10 @@ void App::render()
     // long confirmed (the other leg holds the real count). So: a txid with ANY confirmed leg is
     // confirmed, and we count UNIQUE unconfirmed txids — otherwise the badge sticks on stale 0-conf
     // legs of already-confirmed transactions and double-counts multi-leg ones.
-    {
+    // Recompute only when the tx list actually changed (last_tx_update is bumped on every tx refresh;
+    // size() catches same-second content changes). Otherwise this built two unordered_sets over the whole
+    // wallet tx list every frame just to size a badge.
+    if (state_.last_tx_update != sb_unconf_key_ts_ || state_.transactions.size() != sb_unconf_key_n_) {
         std::unordered_set<std::string> confirmedTxids;
         for (const auto& tx : state_.transactions) {
             if (tx.confirmations >= 1) confirmedTxids.insert(tx.txid);
@@ -1817,8 +1820,11 @@ void App::render()
                 unconfirmedTxids.insert(tx.txid);
             }
         }
-        sbStatus.unconfirmedTxCount = static_cast<int>(unconfirmedTxids.size());
+        sb_unconf_count_  = static_cast<int>(unconfirmedTxids.size());
+        sb_unconf_key_ts_ = state_.last_tx_update;
+        sb_unconf_key_n_  = state_.transactions.size();
     }
+    sbStatus.unconfirmedTxCount = sb_unconf_count_;
 
     // Sidebar minimum height from ui.toml schema (DPI-scaled).
     const float sbMinHeight = sbde("min-height", 360.0f);
@@ -5695,17 +5701,26 @@ bool App::stopDaemonForBootstrap()
 
 double App::getDaemonMemoryUsageMB() const
 {
+    // The Mining tab reads this every frame, but the probe is expensive (Linux embedded/external paths
+    // scan /proc; macOS forks a shell). Throttle to ~1.5s so a 60Hz caller doesn't hammer the OS.
+    const double now = ImGui::GetTime();
+    if (daemon_mem_probe_at_ > 0.0 && now - daemon_mem_probe_at_ < 1.5)
+        return daemon_mem_cached_mb_;
+    daemon_mem_probe_at_ = now;
+
+    double result = 0.0;
     // If we have an embedded daemon with a tracked process handle, use it
     // directly — more reliable than a process scan since we own the handle.
     if (daemon_controller_ && daemon_controller_->isRunning()) {
         double mb = daemon_controller_->memoryUsageMB();
         daemon_mem_diag_ = "embedded";
-        if (mb > 0.0) return mb;
+        result = (mb > 0.0) ? mb : util::Platform::getDaemonMemoryUsageMB();
     } else {
         daemon_mem_diag_ = "process scan";
+        result = util::Platform::getDaemonMemoryUsageMB();  // external daemon
     }
-    // Fall back to platform-level process scan (external daemon)
-    return util::Platform::getDaemonMemoryUsageMB();
+    daemon_mem_cached_mb_ = result;
+    return result;
 }
 
 // ============================================================================