chore: update intro hero copy and sync chapter test comments

Author: ofriw

website/src/components/SiteHero/index.tsx

@@ -3,17 +3,24 @@ import { type ReactNode } from 'react';
 
 import styles from './index.module.css';
 
+/* Orientation first: the H1 states both what this is (a field guide) and its
+   payoff (agents whose output you can stand behind). The recognition hook lives
+   in the lead, one layer down.
+
+   Copy note: no adversarial/security metaphors and none of the words other
+   sections own (operator, machine, run, ships, trust, verify, decision, final
+   call, discipline). */
 function HeroCopy() {
   return (
     <div className={styles.copy}>
-      <p className={styles.eyebrow}>For people responsible for what ships</p>
+      <p className={styles.eyebrow}>For people taking back control</p>
       <Heading as="h1" className={styles.title}>
-        It looks done. That’s when the real work starts.
+        A field guide to AI agents you can stand behind.
       </Heading>
       <p className={styles.lead}>
         An agent can turn a request into a convincing change before you have
-        time to understand its consequences. Keep the speed—and know what you
-        are shipping.
+        time to understand its consequences. This book is how you keep that
+        speed—and stay accountable.
       </p>
     </div>
   );

website/src/navigation/chapters.test.ts

@@ -102,14 +102,14 @@ test('exactly one beforeGroups entry occupies index 0 so section numbers stay st
   );
 });
 
-test('first numbered chapter is how-llms-work (SiteHero CTA depends on this)', () => {
-  // SiteHero derives number, route, and title from the first numbered chapter.
-  // If the first numbered chapter changes, the CTA must update accordingly.
+test('first numbered chapter is how-llms-work (intro Next link depends on this)', () => {
+  // The intro page's "Next:" link points at the first numbered chapter. If the
+  // first numbered chapter changes, that link must be updated with it.
   const firstNumbered = chapters.find(isNumbered);
   assert.equal(
     firstNumbered?.id,
     'how-llms-work',
-    'SiteHero CTA title "LLMs Demystified" is coupled to this chapter ID'
+    'intro.mdx Next link "LLMs Demystified" is coupled to this chapter ID'
   );
 });
 
@@ -185,8 +185,8 @@ test('Toolbox is the final category before About and has no chapter numbers', ()
 
 test('chapter titles match the frontmatter titles the sidebar displays', () => {
   // The sidebar label comes from each doc's frontmatter, while chapters.ts
-  // titles are the declared single source of truth (chapters.ts header);
-  // SiteHero consumes the first one. Drift here desyncs those consumers.
+  // titles are the declared single source of truth (chapters.ts header).
+  // Drift here desyncs the two descriptions of the same chapter.
   for (const group of chapterGroups) {
     for (const chapter of group.chapters) {
       assert.equal(