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/apps/epic/static/apps/epic/room.js

@@ -78,7 +78,11 @@
             var sw = stageEl.offsetWidth  - 24;  // subtract padding (0.75rem × 2)
             var sh = stageEl.offsetHeight - 24;
             if (sw > 0 && sh > 0) {
-                var cardW = Math.min(sw * 0.4, sh * 0.8 * 5 / 8);
+                // Clamp between 90px (never tiny in landscape) and 160px (never
+                // dominant on very wide/tall viewports).  In portrait, skip the
+                // floor so small modals still scale down naturally.
+                var cardW = Math.min(sw * 0.4, sh * 0.8 * 5 / 8, 160);
+                if (isLandscape) { cardW = Math.max(cardW, 90); }
                 overlay.style.setProperty('--sig-card-w', cardW + 'px');
             }
         }