Rebuild navbar, hero, and feature sections in adaline style

- navbar: sticky, transparent to blur-on-scroll, wordmark + mono nav links +
  theme toggle + Download CTA, Reicon Menu/Xmark icons (components/layout)
- theme-toggle: Reicon Sun/Moon icons
- hero: meadow badge, tight Instrument Sans headline, Download + How-it-works
  CTAs, availability line, framed dashboard shot (components/sections)
- features: five stacked heading-over-panel sections mapping the org chart,
  office, messages, connectors and cost-control screens
- ui/media-frame: shared framed product-shot panel
- reveal: progressive enhancement — content is visible without JS and only
  hidden once the js class is present, then revealed on scroll
- remove the superseded flat navbar/hero/features components

Verified: next build green; desktop + mobile screenshots reviewed.

landing/components/ui/media-frame.tsx

@@ -0,0 +1,29 @@
+/** Framed product screenshot panel: rounded, bordered, soft shadow on the page. */
+export function MediaFrame({
+  src,
+  alt,
+  priority = false,
+  className = "",
+}: {
+  src: string;
+  alt: string;
+  priority?: boolean;
+  className?: string;
+}) {
+  return (
+    <div
+      className={`overflow-hidden rounded-xl border border-[var(--border)] bg-[var(--panel-illustration)] shadow-[0_24px_70px_-28px_rgba(10,29,8,0.3)] md:rounded-2xl ${className}`}
+    >
+      <img
+        src={src}
+        alt={alt}
+        width={2400}
+        height={1600}
+        loading={priority ? "eager" : "lazy"}
+        decoding="async"
+        fetchPriority={priority ? "high" : "auto"}
+        className="block h-auto w-full"
+      />
+    </div>
+  );
+}