fix(mobile): MCP showcase columns busted out of grid by ~30 px

The .landing-mcp-showcase grid switches to a single column at ≤768 px,
but each grid item still rendered ~370 px wide on a 342 px parent — a
classic CSS Grid `min-width: auto` issue, where grid items refuse to
shrink below their intrinsic content width. The right column embeds a
fake terminal with a `<pre>`-formatted code sample whose lines are
longer than the viewport, dragging the column past the container edge
and producing the residual 5 px horizontal scroll on the landing page.

min-width: 0 on both columns lets the grid item shrink to fit; the
inner `<pre>` already has overflow-x: auto so it h-scrolls within its
own box, which is the correct behavior for a code sample.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: Sbussiso

frontend/src/styles/landing.css

@@ -2186,6 +2186,18 @@
     grid-template-columns: 1fr;
     gap: 2rem;
   }
+
+  /* Grid items default to min-width: auto, which is the intrinsic size of
+     their content. The .landing-mcp-right column embeds a fake terminal
+     code block with `white-space: pre` lines longer than the viewport;
+     without min-width: 0 the grid item refuses to shrink below content
+     width and pushes 5–30 px past the container edge. min-width: 0 lets
+     the column shrink to fit; the inner pre still h-scrolls inside its
+     own box, which is the correct behavior for a code sample. */
+  .landing-mcp-left,
+  .landing-mcp-right {
+    min-width: 0;
+  }
 }
 
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