feat(site): migrate from Next.js to Astro

Replace Next.js 16 + React 19 with Astro 5. Same visual design,
same deploy pipeline, zero client-side framework.

- All components rewritten as .astro files
- Dark mode via inline scripts (no React context)
- Timeline animation via IntersectionObserver script
- Nav active state computed at build time
- Self-hosted Source Code Pro woff2 fonts
- Drop Font Awesome (icons were never loaded)
- Drop unused headshot PNG (1MB, unreferenced)
- Fix pfSense hardware refs (Netgate 1100, not N100)
- Output: 212KB static HTML vs 2.6MB before
- JS shipped: ~700 bytes inline vs ~130KB React runtime

src/components/Hero.astro

@@ -0,0 +1,71 @@
+<section class="mb-16">
+  <div class="flex flex-col gap-1ch">
+    <div>
+      <p class="font-mono text-sm font-bold text-[var(--color-text)]">
+        <span
+          class="text-[var(--color-accent-green)] select-none mr-1ch"
+          aria-hidden="true"
+        >
+          ❯
+        </span>
+        tyler koenig
+      </p>
+      <p class="font-mono text-sm text-[var(--color-text-label)] mt-0.5">
+        Security Operations · Self-Hosted Infrastructure
+      </p>
+    </div>
+
+    <p class="font-mono text-sm text-[var(--color-text)] leading-relaxed opacity-70">
+      Homelab runs 30+
+      services across segmented VLANs — pfSense, Authentik SSO, full
+      observability stack. Write software too: mobile apps, Go backends,
+      open protocols. Daily drivers, all of it.{" "}
+      <span
+        class="animate-cursor text-[var(--color-accent-green)]"
+        aria-hidden="true"
+      >
+        █
+      </span>
+    </p>
+
+    <div class="flex flex-wrap items-center gap-x-1ch gap-y-half-lh">
+      <span class="font-mono text-sm text-[var(--color-accent-green)]">
+        ● available
+      </span>
+      <a
+        href="https://github.com/lerko96"
+        target="_blank"
+        rel="noopener noreferrer"
+        aria-label="GitHub"
+        class="font-mono text-sm text-[var(--color-text-label)] hover:text-[var(--color-text)]"
+      >
+        [github]
+      </a>
+      <a
+        href="https://gitea.lerkolabs.com/lerko"
+        target="_blank"
+        rel="noopener noreferrer"
+        aria-label="Gitea"
+        class="font-mono text-sm text-[var(--color-text-label)] hover:text-[var(--color-text)]"
+      >
+        [gitea]
+      </a>
+      <a
+        href="https://www.linkedin.com/in/tyler-koenig"
+        target="_blank"
+        rel="noopener noreferrer"
+        aria-label="LinkedIn"
+        class="font-mono text-sm text-[var(--color-text-label)] hover:text-[var(--color-text)]"
+      >
+        [linkedin]
+      </a>
+      <a
+        href="mailto:tyler@lerkolabs.com"
+        aria-label="Email"
+        class="font-mono text-sm text-[var(--color-text-label)] hover:text-[var(--color-text)]"
+      >
+        [email]
+      </a>
+    </div>
+  </div>
+</section>