seat tray: tray.js, SCSS, FTs, Jasmine specs

- new apps.epic.static tray.js: IIFE with drag-open/click-close/wobble
  behaviour; document-level pointermove+mouseup listeners; reset() for
  Jasmine afterEach; try/catch around setPointerCapture for synthetic events
- _room.scss: #id_tray_wrap fixed-right flex container; #id_tray_handle +
  #id_tray_grip (box-shadow frame, transparent inner window, border-radius
  clip); #id_tray_btn grab cursor; #id_tray bevel box-shadows, margin-left
  gap, height removed (align-items:stretch handles it); tray-wobble keyframes
- _applets.scss + _game-kit.scss: z-index raised (312-318) for primacy over
  tray (310)
- room.html: #id_tray_wrap + children markup; tray.js script tag
- FTs test_room_tray: 5 tests (T1-T5); _simulate_drag via execute_script
  pointer events (replaces unreliable ActionChains drag); wobble asserts on
  #id_tray_wrap not btn
- static_src/tests/TraySpec.js + SpecRunner.html: Jasmine unit tests for
  all tray.js branches

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/static_src/scss/_applets.scss

@@ -93,7 +93,7 @@
         position: fixed;
         bottom: 4.2rem;
         right: 0.5rem;
-        z-index: 202;
+        z-index: 314;
     }
 }
 
@@ -104,7 +104,7 @@
     position: fixed;
     bottom: 6.6rem;
     right: 1rem;
-    z-index: 201;
+    z-index: 312;
 }
 
 // In landscape: shift gear btn and applet menus left of the footer right sidebar