landscape layout: remove max-width cutoff; sig-select stage/grid polish

- All landscape @media queries: drop and (max-width: 1440px) — sidebar layout
  now activates for all landscape orientations regardless of viewport width
- _base.scss landscape container: add max-width:none to override the
  @media(min-width:1200px) rule and fill the full space between sidebars
- sig-select sig-deck-grid: landscape now 9×2 @ 3rem cards; 18×1 at ≥1100px
  (bumped from 992px to avoid last-card clip); card text scales with --sig-card-w
- sig-stat-block: flex:1→flex:0 0 auto with width:--sig-card-w so it matches
  preview card dimensions instead of stretching across the full stage
- room.js sizeSigModal: landscape card width clamped to [90px, 160px]

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

src/static_src/scss/_game-kit.scss

@@ -3,7 +3,7 @@
     bottom: 0.5rem;
     right: 0.5rem;
 
-    @media (orientation: landscape) and (max-width: 1440px) {
+    @media (orientation: landscape) {
         right: 0.5rem;
         bottom: 0.5rem;
         top: auto;
@@ -45,7 +45,7 @@
     z-index: 316;
     overflow: hidden;
 
-    @media (orientation: landscape) and (max-width: 1440px) {
+    @media (orientation: landscape) {
         $sidebar-w: 4rem;
         // left: $sidebar-w;
         right: $sidebar-w;