refactor(web): decompose 358-LOC manifesto into 9 section components

app/[locale]/manifesto/page.tsx: 358 LOC -> 22-LOC composition shell.

components/manifesto/sections/:
- hero.tsx
- pain-points.tsx
- indistinguishable.tsx (the 'AI vs senior engineer' argument)
- token-cost.tsx
- cognitive-load.tsx
- principles.tsx
- core-loop.tsx
- future.tsx
- final-cta.tsx

Each section 26-68 LOC. Copy unchanged; section order unchanged.
Same i18n namespace ('manifesto'). Renders identically to baseline
in all 4 locales (en/ko/ja/zh).

packages/web/components/manifesto/sections/indistinguishable.tsx

@@ -0,0 +1,39 @@
+import type { JSX } from "react"
+import { getTranslations } from "next-intl/server"
+import { Check } from "lucide-react"
+import { Section } from "@/components/ui/section"
+
+export async function IndistinguishableSection(): Promise<JSX.Element> {
+  const t = await getTranslations("manifesto")
+  const indistinguishableKeys = [
+    "patterns",
+    "errorHandling",
+    "tests",
+    "noSlop",
+    "comments",
+  ] as const
+
+  return (
+    <Section data-section="manifesto-indistinguishable" className="mx-auto max-w-3xl">
+      <h2 className="mb-8 text-3xl font-bold md:text-4xl">{t("indistinguishable.title")}</h2>
+
+      <p className="text-muted-foreground mb-8 text-xl">{t("indistinguishable.subtitle")}</p>
+
+      <div className="mb-10 grid gap-6">
+        {indistinguishableKeys.map((key) => (
+          <div
+            key={key}
+            className="bg-secondary/30 border-border/50 flex items-start gap-4 rounded-lg border p-4"
+          >
+            <Check className="h-6 w-6 shrink-0 text-green-500" />
+            <span>{t(`indistinguishable.items.${key}`)}</span>
+          </div>
+        ))}
+      </div>
+
+      <blockquote className="border-primary bg-primary/5 rounded-r-lg border-l-4 py-4 pl-6 text-2xl font-light italic">
+        {t("indistinguishable.quote")}
+      </blockquote>
+    </Section>
+  )
+}