fix(landing): align FAQ chapter to centered-axis pattern matching pricing

Owner directive (2026-06-07): "layout u bozuyor biraz ortali oldugu icin,
pricing'de yaptigin gibi yap" — the FAQ chapter was the only chapter using
wrap-narrow (840px tight-center) while every other chapter uses wrap
(1280px) with an inline-centered intro block. The inconsistency broke
page rhythm.

Mirror the Pricing chapter pattern shipped in 48cfe06 (web/index.html
L461-468):
  - section uses regular .wrap container (1280px) instead of .wrap-narrow
  - intro block .rev: max-width:880px; margin:0 auto; text-align:center
  - .rule: margin-left:auto; margin-right:auto
  - .faq details list: max-width:840px; margin auto (preserves the
    comfortable reading width of wrap-narrow inside a centered column
    while the questions/answers stay left-aligned by default)

Also adds id="faq" to the chapter for anchor parity with id="pricing".

Files:
  - web/index.html L1292-1301 (FAQ intro block — was using wrap-narrow
    + no centering styles → now matches pricing's centered-axis pattern)
  - mirrors web/index.html L461-468 (pricing intro block — the
    canonical centered-axis treatment)

No content change. Visual treatment only — every <details> question +
answer body is byte-identical.

web/index.html

@@ -1290,15 +1290,15 @@ commit_strong_cadence, commit_fix_heavy</span></pre>
 <hr class="sep">
 
 <!-- ═══════════════════════════════════════ FAQ ═══════════════════════════════════════ -->
-<section class="chapter">
-  <div class="wrap-narrow">
-    <div class="rev">
+<section class="chapter" id="faq">
+  <div class="wrap">
+    <div class="rev" style="max-width:880px;margin:0 auto;text-align:center">
       <p class="section-num">§ 12 · faq</p>
       <h2 class="h2">Questions before the call.</h2>
-      <div class="rule"></div>
+      <div class="rule" style="margin-left:auto;margin-right:auto"></div>
     </div>
 
-    <div class="faq rev">
+    <div class="faq rev" style="max-width:840px;margin-left:auto;margin-right:auto">
       <details>
         <summary>How much does Insights cost?</summary>
         <p>Pro tier is <strong>$20 per seat per month</strong>. Per-seat means per member of your org (active or invited). Billed monthly. No annual variant, no volume discount, no Enterprise SKU, no free tier, no trial. Self-serve at <a href="https://platform.context-mode.com">platform.context-mode.com</a>.</p>