refactor(web): decompose 832-LOC landing into 10 section components

app/_components/landing-page.tsx: 832 LOC -> 33-LOC composition shell.
Each section becomes a focused, named component under
components/landing/sections/:

- hero.tsx: terminal headline + install command + primary CTA
- ultrawork.tsx: ultrawork mode pitch
- sisyphus.tsx: Sisyphus orchestrator showcase
- prometheus-atlas.tsx: planner + executor pair (was amber+indigo,
  now violet — single secondary accent)
- hephaestus.tsx: code surgeon (was orange, now cyan)
- team-mode.tsx: parallel team coordination (was fuchsia/purple/cyan
  gradient, now solid cyan headline + violet skills accent)
- sub-agents.tsx: explore/librarian/oracle/multimodal etc.
- architecture.tsx: 4-tier diagram
- reviews.tsx: testimonials (Star kept text-cyan-500 / fill-cyan-500,
  on-brand)
- cta.tsx: final call-to-action

components/landing/constants.ts (new):
- SUB_AGENT_KEYS, AGENT_STYLES, PRINCIPLE_KEYS, PRINCIPLE_ICONS,
  REVIEW_KEYS, CATEGORY_ROUTING, SKILL_INJECTIONS
- Single source of truth for agent/principle/review metadata used
  across sections

components/icons/github-icon.tsx (new):
- Extracted inline SVG into a typed component with default
  aria-hidden and overridable size/className

Color consolidation: 9-color rainbow per-section -> cyan (primary)
+ violet (secondary, agent identity) + neutral grays + status colors
only. 'Evolution not revolution': dark + cyan brand soul intact.

packages/web/components/landing/sections/architecture.tsx

@@ -0,0 +1,46 @@
+import type { JSX } from "react"
+import { getTranslations } from "next-intl/server"
+import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card"
+import { PRINCIPLE_KEYS, PRINCIPLE_ICONS } from "@/components/landing/constants"
+
+export async function ArchitectureSection(): Promise<JSX.Element> {
+  const t = await getTranslations("landing")
+
+  return (
+    <section className="bg-black py-24" data-section="architecture">
+      <div className="reveal-on-enter container mx-auto px-4 md:px-6">
+        <div className="mb-16 text-center">
+          <h2 className="mb-4 text-4xl font-bold text-white md:text-5xl">
+            {t("architecture.title")}
+          </h2>
+          <p className="text-xl text-zinc-400">{t("architecture.subtitle")}</p>
+        </div>
+
+        <div className="mx-auto grid max-w-5xl grid-cols-1 gap-6 md:grid-cols-2 lg:grid-cols-3">
+          {PRINCIPLE_KEYS.map((key) => {
+            const Icon = PRINCIPLE_ICONS[key]
+            return (
+              <div key={key}>
+                <Card className="h-full border-zinc-800 bg-zinc-900/30">
+                  <CardHeader>
+                    <div className="w-fit rounded-lg bg-zinc-800 p-2">
+                      <Icon className="h-5 w-5 text-zinc-300" />
+                    </div>
+                    <CardTitle className="mt-3 text-lg text-white">
+                      {t(`architecture.principles.${key}.title`)}
+                    </CardTitle>
+                  </CardHeader>
+                  <CardContent>
+                    <p className="text-sm leading-relaxed text-zinc-400">
+                      {t(`architecture.principles.${key}.description`)}
+                    </p>
+                  </CardContent>
+                </Card>
+              </div>
+            )
+          })}
+        </div>
+      </div>
+    </section>
+  )
+}