feat: redesign landing page with brand system and section blocks

Refresh the homepage around new hero/services/roadmap sections, shared design tokens, and updated brand assets.

Co-authored-by: Cursor <cursoragent@cursor.com>

styles/design-system/grid.css

@@ -0,0 +1,28 @@
+@layer utilities {
+  /*
+   * Legacy section grid — prefer page-atmosphere__grid for continuity.
+   * Kept for rare accent use; same scale/opacity family as the global grid.
+   */
+  .section-pattern-grid {
+    position: absolute;
+    inset: 0;
+    opacity: 0.022;
+    background-image:
+      linear-gradient(to right, currentColor 1px, transparent 1px),
+      linear-gradient(to bottom, currentColor 1px, transparent 1px);
+    background-size: 4rem 4rem;
+    color: var(--foreground);
+  }
+
+  .section-pattern-grid--accent {
+    opacity: 0.028;
+  }
+
+  .dark .section-pattern-grid {
+    opacity: 0.028;
+  }
+
+  .dark .section-pattern-grid--accent {
+    opacity: 0.034;
+  }
+}