feat(sections): add ThreeAmWalkthrough component

Replaces DualValueProps + ProductShowcase with a single before/after
split: a styled <pre> block (the 'without' state) next to the
existing /product/error-detail.png screenshot (the 'with' state).
Three short callouts below.

Section anchor #walkthrough is the target for the Hero's
'See it in action ↓' secondary CTA (added in Task 4).

The 'without' panel is implemented as a styled <pre> per the spec —
no asset production required. A future phase may swap to a recorded
terminal screencap; that swap is a one-component change.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/sections/ThreeAmWalkthrough.astro

@@ -0,0 +1,104 @@
+---
+import Lightbox from '../Lightbox.astro';
+
+interface Callout {
+  title: string;
+  body: string;
+}
+
+const callouts: Callout[] = [
+  {
+    title: 'Cross-service correlation.',
+    body: 'Every exchange carries its correlation ID forward. One click jumps to what the downstream route did with the same message.',
+  },
+  {
+    title: 'Runtime detail, not guesswork.',
+    body: 'Circuit breaker tripped. Fallback path ran. Request tried backend:80. The pieces a 3 AM page actually needs — already captured.',
+  },
+  {
+    title: 'The whole story of a failure.',
+    body: 'Exception class, message, stack trace, headers, payload — all pinned to the exchange. No log-grepping tour.',
+  },
+];
+---
+<section id="walkthrough" class="border-b border-border bg-bg">
+  <div class="max-w-content mx-auto px-6 py-24 md:py-32">
+    <div class="max-w-3xl mb-14 md:mb-20">
+      <p class="text-cyan font-mono text-xs tracking-[0.25em] uppercase mb-4">// When something breaks</p>
+      <h2 class="text-hero font-bold text-text mb-5">
+        The 3 AM page. With and without Cameleer.
+      </h2>
+      <p class="text-lg text-text-muted leading-relaxed">
+        Same Camel app. Same failed exchange. Different night.
+      </p>
+    </div>
+
+    <div class="grid md:grid-cols-2 gap-6 md:gap-8 items-stretch">
+      <div class="without-card relative rounded-lg border border-dashed border-border-strong bg-bg overflow-hidden">
+        <div class="px-5 pt-5 pb-3 font-mono text-[11px] tracking-[0.2em] uppercase text-text-faint border-b border-border">
+          Without Cameleer · 03:12 AM
+        </div>
+        <pre class="font-mono text-[13px] leading-[1.65] text-text-muted px-5 py-5 overflow-x-auto whitespace-pre"><code><span class="text-text">$</span> kubectl logs camel-router-7d4f8c
+<span class="text-rose">ERROR</span> org.apache.camel.CamelExecutionException
+  at org.apache.camel.processor.SendProcessor.process
+  at org.apache.camel.processor.Pipeline.process
+  ...
+
+<span class="text-text">$</span> grep "order-842" *.log
+router-3.log: <span class="text-accent">WARN</span>  exchange order-842 stuck in saga-fulfillment
+router-3.log: <span class="text-rose">ERROR</span> processor backend:80 → connect timeout
+
+<span class="text-text">$</span> ssh prod-integration-3
+prod-integration-3 $ kubectl logs ...
+
+&gt; <span class="text-cyan">slack #integration-team</span>
+  "anyone know why order-842 is stuck??"
+  <span class="text-text-faint">[3 of 4 reactions, no answer]</span>
+
+<span class="text-accent">~47 min later: someone wakes up an SRE.</span></code></pre>
+      </div>
+
+      <figure class="with-card relative rounded-lg border border-border-strong bg-bg-elevated overflow-hidden">
+        <div class="px-5 pt-5 pb-3 font-mono text-[11px] tracking-[0.2em] uppercase text-accent border-b border-border">
+          With Cameleer · 30 sec
+        </div>
+        <Lightbox
+          src="/product/error-detail.png"
+          alt="Cameleer Mission Control — failed exchange order-842 with full execution context"
+          width={1920}
+          height={945}
+          loading="lazy"
+          imgClass="block w-full h-auto"
+        />
+        <div class="px-5 py-4 font-mono text-[13px] leading-[1.6] text-text-muted border-t border-border">
+          <span class="text-accent">▸</span> Open exchange <span class="text-text">order-842</span> → see the failure pinned → click <span class="text-text">Replay</span> after fix.
+        </div>
+        <div class="absolute inset-0 ring-1 ring-inset ring-accent/10 pointer-events-none rounded-lg"></div>
+      </figure>
+    </div>
+
+    <ul class="grid md:grid-cols-3 gap-6 md:gap-8 mt-14">
+      {callouts.map((c, i) => (
+        <li class="relative pl-10">
+          <span
+            class="absolute left-0 top-0 inline-flex items-center justify-center w-7 h-7 rounded-full border border-accent/40 bg-accent/10 text-accent font-mono text-xs"
+            aria-hidden="true"
+          >
+            {String(i + 1).padStart(2, '0')}
+          </span>
+          <h3 class="text-text font-semibold mb-1.5">{c.title}</h3>
+          <p class="text-text-muted leading-relaxed">{c.body}</p>
+        </li>
+      ))}
+    </ul>
+  </div>
+</section>
+
+<style>
+  .with-card {
+    box-shadow:
+      0 1px 0 rgba(240, 180, 41, 0.08) inset,
+      0 30px 60px -25px rgba(0, 0, 0, 0.7),
+      0 12px 30px -12px rgba(0, 0, 0, 0.5);
+  }
+</style>