feat(marketing): redesign landing as "trusted infrastructure"

Re-skins the playful/consumer feel into disciplined agent-infrastructure,
keeping the animated hero canvas (re-themed) and adding the hierarchy story.

- Palette: re-point coral→ember (#E0584A); add ink/surface/mist/slate-light/
  azure/teal tokens. One accent per viewport; retire the black/coral split-
  headline pattern across all 8 headings (single ink color).
- Typography: hero/section weights 800→~650-675, tighter tracking, smaller
  hero size; uppercase eyebrow label.
- Hero: dark ink base with glowing azure/indigo + faint ember canvas blooms;
  light copy; new positioning ("Build safe, scalable agentic systems" + the
  single-agent-to-company subhead); ember primary CTA + ghost "Read the docs".
- Imagery overhaul (code-built, no mascots): AgentToken chips (CrewStrip,
  OneClick card, footer), AlwaysOn rebuilt as a terminal/log with an approval
  line, SkillsShowcase as duotone lucide cards on Mist, Security as a shield/
  lock motif.
- New HierarchyDiagram section ("One agent, or a whole org chart"): SVG org
  chart with an azure active path and teal human-approval checkpoints on
  sandbox-leaving actions.
- Tests: dark-hero/terminal/eyebrow contrast fixed to AA; refreshed the
  marketing @visual baseline (hero masked).

Co-Authored-By: Claude Opus 4.8 <[email protected]>

frontend/src/app/(marketing)/marketing/page.tsx

@@ -1,6 +1,7 @@
 import type { Metadata } from "next";
 
 import { Faq } from "@/components/marketing/Faq";
+import { HierarchyDiagram } from "@/components/marketing/HierarchyDiagram";
 import { MarketingNav } from "@/components/marketing/Nav";
 import {
   AlwaysOn,
@@ -34,6 +35,7 @@ export default function MarketingPage() {
         <Works />
         <AlwaysOn />
         <SkillsShowcase />
+        <HierarchyDiagram />
         <Security />
         <Faq />
       </main>