feat(identity): real author photo across the site + About page rewrite

The photo is the identity evidence the external review flagged as the biggest
gap. One source image (Pictures/Professional Portrait with Blue Gradient
Background.png, 1254x1254), two sizes, WebP first with a JPEG fallback —
continuous tone is the case where WebP/JPEG beat PNG:

  640x640  42 KB JPG / 26 KB WebP   About page (190 CSS px)
  128x128   3 KB JPG /  2 KB WebP   author card + home hero avatar

It now appears in the About hero, the author card at the end of every post, the
home hero (both languages), and JSON-LD Person.image — the node search engines
read to associate the name with a face.

About went from 1,024 characters to five sections: identity with photo, "By the
numbers" (162 containers / 3 hosts / 71 essays / 0 hosting companies between me
and the servers), the real tech stack in four columns, the Hoelee Enterprise
block (website design and development is the main business, email hosting
secondary), and a contact split between hiring and business.

Also: the headshot's dark-blue background sits close to the page background, so
the photo, hero avatar and card avatar get a faint brand ring plus shadow.

Pictures/ keeps the converted JPG master next to the untouched PNG.

src/pages/index.astro

@@ -25,7 +25,20 @@ const featuredPosts = featured.length === 4 ? featured : posts.slice(0, 4);
 
 <BaseLayout title={SITE.title} description={SITE.description} altLocaleUrl={`${SITE.url}/zh/`}>
   <section class="hero">
-    <h1>{SITE.author} — full-stack developer &amp; DevOps engineer</h1>
+    <div class="hero-id">
+      <picture>
+        <source srcset={SITE.photo.smallWebp} type="image/webp" />
+        <img
+          class="hero-photo"
+          src={SITE.photo.small}
+          alt={`${SITE.author} (${SITE.handle})`}
+          width="72"
+          height="72"
+          decoding="async"
+        />
+      </picture>
+      <h1>{SITE.author} — full-stack developer &amp; DevOps engineer</h1>
+    </div>
     <p class="hero-sub">
       I run <strong>162 containers across three self-managed hosts</strong> — client sites, a
       mail platform, CI/CD, workflow automation and this blog — and I build web systems for