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/anti_tank_emplacement.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 126 126"><g><path d="M99.866 31A54.163 54.163 0 0 0 84.65 16H121v15H99.866Zm1.691 24v14H49.99v-5H64l5-5h15l13-10-13-10H69l-5-5H49.993V16h18.6s32.964-.032 32.964 39Zm-5.918 19v16h-37.2V74h37.2Zm6.761 20 10.99 16H39l10.99-16h52.41Z" style="fill-rule:evenodd;fill:#679552"/><circle cx="18" cy="24" r="9" fill="#fff"/><path fill="#fff" fill-rule="evenodd" d="M5 34v40h5v37h16V74h5V34H5Z"/><path fill="#fff" fill-rule="evenodd" d="M82 55H66l-4 5H39V38h23l4 5h16l8 6Z"/></g></svg>