feat: S/M/L height drives mode-select row vs column layout

When height is set to S, mode-select collapses to a row (mode button +
compact tools toggle side by side). M and L keep the vertical column
layout where each control gets its own full-width row. Driven by
data-size attribute set in JS so the switch is instant on click, not
reliant on a viewport media query. Removed the redundant max-height
landscape query.

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

cortex/static/app.js

@@ -156,12 +156,16 @@
             inputEl.style.height = Math.max(Math.min(sh, maxHeight), minH) + 'px';
         }
 
+        const modeSelectEl = document.getElementById('mode-select');
+
         function updateHeightUI() {
             if (!heightCycleBtn) return;
             const idx = HEIGHT_SIZES.indexOf(maxHeight);
             const i = idx >= 0 ? idx : 0;
             heightCycleBtn.textContent = HEIGHT_LABELS[i];
             heightCycleBtn.title = HEIGHT_TITLES[i];
+            // Drive row/column layout via data attribute
+            if (modeSelectEl) modeSelectEl.dataset.size = HEIGHT_LABELS[i].toLowerCase();
         }
 
         if (heightCycleBtn) {