z-index audit + aperture fill + resize:end debounce + landscape sig-grid cap

- #id_aperture_fill: position:fixed→absolute (clips to .room-page, avoids h2/navbar);
  z-index 105→90 (below blur backdrops at z-100); landscape override removed (inset:0 works both orientations)
- _base.scss: landscape footer z-index:100 (matches navbar); corrects unset z-index
- _room.scss: fix stale "navbar z-300" comment; landscape sig-deck-grid columns
  repeat(9,1fr)→repeat(9,minmax(0,90px)) to cap card size on wide viewports
- room.js: add resize:end listeners for scaleTable + sizeSigModal; new IIFE dispatches
  resize:end 500ms after resize stops so both functions re-measure settled layout
- tray.js: extract _reposition() from inline resize handler; wire to both resize and
  resize:end so tray repositions correctly after rapid resize or orientation change

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

src/static_src/scss/_room.scss

@@ -40,6 +40,27 @@ html:has(.gate-backdrop) {
     overflow: hidden;
 }
 
+// Aperture fill — solid --duoUser layer that covers the game table (.room-page).
+// Uses position:absolute so it's clipped to .room-page bounds (overflow:hidden),
+// naturally staying below the h2 title + navbar/footer in both orientations.
+// Sits at z-90: below blur backdrops (z-100) which render on top via backdrop-filter.
+// Fades in/out via opacity transition when a backdrop class is present.
+#id_aperture_fill {
+    position: absolute;
+    inset: 0;
+    background: rgba(var(--duoUser), 1);
+    z-index: 90;
+    pointer-events: none;
+    opacity: 0;
+    transition: opacity 0.15s ease;
+}
+
+html:has(.gate-backdrop) #id_aperture_fill,
+html:has(.sig-backdrop) #id_aperture_fill,
+html:has(.role-select-backdrop) #id_aperture_fill {
+    opacity: 1;
+}
+
 .gate-backdrop {
     position: fixed;
     inset: 0;
@@ -781,8 +802,8 @@ $card-h: 60px;
 // Landscape mobile — aggressively scale down to fit short viewport
 @media (orientation: landscape) and (max-width: 1440px) {
     // Sink navbar below gate/role-select overlays when a modal is open.
-    // Landscape navbar z-index is 300 (_base.scss); gate-backdrop/overlay are
-    // 100/120, so the sidebar bleeds over the modal without this override.
+    // Landscape navbar z-index is 100 (_base.scss); gate-backdrop/overlay are
+    // 100/120 — same level causes paint-order ties so we drop it to 50.
     html:has(.gate-backdrop) body .container .navbar,
     html:has(.role-select-backdrop) body .container .navbar {
         z-index: 50;
@@ -959,7 +980,7 @@ html:has(.sig-backdrop) {
 
 .sig-card {
     aspect-ratio: 5 / 8;
-    border-radius: 3px;
+    border-radius: 0.4rem;
     background: rgba(var(--priUser), 0.97);
     border: 1px solid rgba(var(--secUser), 0.3);
     position: relative;
@@ -1061,7 +1082,7 @@ html:has(.sig-backdrop) {
     .sig-overlay   { padding-left: 4rem; }
     .sig-modal     { max-width: none; }
     .sig-deck-grid {
-        grid-template-columns: repeat(9, 1fr);
+        grid-template-columns: repeat(9, minmax(0, 90px));
         margin: 0;
     }
 }