Release 3.8.1.1: lighter idle UI poll, core cache, multicore ping.

Reduce idle CPU (cheap PollUI, binary cache, logbuf cap, DOM fingerprint),
speed ping/AWG HostPort, CopyBuffer pool; ship arm64 build and update notes.

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/appui/index.html

@@ -46,7 +46,7 @@
       <div class="brand-wrap">
         <div class="brand-row">
           <h1 class="brand">Navis</h1>
-          <span class="badge-ver" id="badgeVer">3.8.0</span>
+          <span class="badge-ver" id="badgeVer">3.8.1</span>
         </div>
         <p class="tagline">Быстрый клиент · Naive · Hy2 · AWG · Xray</p>
       </div>