feat: stratagem icons, session summary, queue preview, UX polish

- Download 65 SVG icons from community repo (scripts/download-icons.js)
- Gold CSS filter on all icons to match game theme
- Session summary modal with score/accuracy/top stratagems
- Queue preview strip (next 3 stratagems with icons)
- Score popup animation, icon shake on wrong input
- Icons in history, leaderboard, and best-per-stratagem tables
- server.js: icon fields on all stratagems, ELO in lobby-update WS events

public/icons/hmg_emplacement.svg

@@ -0,0 +1,7 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 126 126">
+  <path fill="#679552" fill-rule="evenodd" d="M99.866,31A54.163,54.163,0,0,0,84.65,16H121V31H99.866Zm1.691,24V69H49.99V63H68l2-2,8-1,6-4,3-4-3-4-5-4V42l5-4,3-4-3-4-6-4-8-1-2-2H49.99V16h18.6S101.557,15.968,101.557,55ZM95.639,74V90h-37.2V74h37.2ZM102.4,94l10.99,16H39L49.99,94H102.4Z"/>
+  <path fill="#fff" fill-rule="evenodd" d="M39,28V40H66.25l1.125-1.714h9L77.5,36.571h3.375L83,34l-2.125-2.571H77.5l-1.125-1.714h-9L66.25,28H39Z"/>
+  <path fill="#fff" fill-rule="evenodd" d="M39,46V58H66.25l1.125-1.714h9L77.5,54.571h3.375L83,52l-2.125-2.571H77.5l-1.125-1.714h-9L66.25,46H39Z"/>
+  <circle fill="#fff" cx="18" cy="24" r="9"/>
+  <path fill="#fff" fill-rule="evenodd" d="M5,34V74h5v37H26V74h5V34H5Z"/>
+</svg>