feat(site): add Mastodon rel=me verification link

Add rel=me links to https://mastodon.saillant.cc/@clement in both
page variants (preview + index): head link tag, visible header
social anchor, and JSON-LD sameAs entry. Enables green verified
badge on the Mastodon profile Site field.

src/pages/index.astro

@@ -18,6 +18,7 @@ import { BmuViewer } from '@/components/BmuViewer';
   <meta name="twitter:title" content="L'électron rare — Systèmes électroniques spécifiques" />
   <meta name="twitter:description" content="Conception, mise au point et fiabilisation de systèmes électroniques spécifiques." />
   <meta name="twitter:image" content="https://www.lelectronrare.fr/assets/og-cover.jpg" />
+  <link rel="me" href="https://mastodon.saillant.cc/@clement" />
   <link rel="icon" href="/favicon.svg" type="image/svg+xml" />
   <link rel="preload" href="/assets/models3d/bmu_v2.glb" as="fetch" crossorigin />
   <link rel="preload" href="/assets/models3d/i2c_repeater.glb" as="fetch" crossorigin />
@@ -33,7 +34,7 @@ import { BmuViewer } from '@/components/BmuViewer';
     "founder": { "@type": "Person", "name": "Clément Saillant" },
     "areaServed": "France",
     "serviceType": ["Conception électronique", "Formation PCB et embarqué", "Consulting technique", "Automatisme industriel"],
-    "sameAs": ["https://fr.linkedin.com/in/electron-rare", "https://github.com/electron-rare/"]
+    "sameAs": ["https://fr.linkedin.com/in/electron-rare", "https://github.com/electron-rare/", "https://mastodon.saillant.cc/@clement"]
   }
   </script>
   <style>
@@ -167,6 +168,7 @@ import { BmuViewer } from '@/components/BmuViewer';
       <a href="/consulting/" class="hdr-link">Consulting</a>
       <a href="https://fr.linkedin.com/in/electron-rare" target="_blank" rel="noopener" class="hdr-link hdr-social" title="LinkedIn">in</a>
       <a href="https://github.com/electron-rare/" target="_blank" rel="noopener" class="hdr-link hdr-social" title="GitHub">gh</a>
+      <a href="https://mastodon.saillant.cc/@clement" target="_blank" rel="me noopener" class="hdr-link hdr-social" title="Mastodon">mt</a>
       <a href="/contact/" class="hdr-cta">Contact</a>
     </nav>
     <button class="burger" id="burger-btn" aria-label="Menu">☰</button>

src/pages/preview.astro

@@ -18,6 +18,7 @@ import { BmuViewer } from '@/components/BmuViewer';
   <meta name="twitter:title" content="L'électron rare — Systèmes électroniques spécifiques" />
   <meta name="twitter:description" content="Conception, mise au point et fiabilisation de systèmes électroniques spécifiques." />
   <meta name="twitter:image" content="https://www.lelectronrare.fr/assets/og-cover.jpg" />
+  <link rel="me" href="https://mastodon.saillant.cc/@clement" />
   <link rel="icon" href="/favicon.svg" type="image/svg+xml" />
   <script type="application/ld+json">
   {
@@ -30,7 +31,7 @@ import { BmuViewer } from '@/components/BmuViewer';
     "founder": { "@type": "Person", "name": "Clément Saillant" },
     "areaServed": "France",
     "serviceType": ["Conception électronique", "Formation PCB et embarqué", "Consulting technique", "Automatisme industriel"],
-    "sameAs": ["https://fr.linkedin.com/in/electron-rare", "https://github.com/electron-rare/"]
+    "sameAs": ["https://fr.linkedin.com/in/electron-rare", "https://github.com/electron-rare/", "https://mastodon.saillant.cc/@clement"]
   }
   </script>
   <style>
@@ -154,6 +155,7 @@ import { BmuViewer } from '@/components/BmuViewer';
       <a href="https://www.lelectronrare.fr/#a-propos" class="hdr-link">Consulting</a>
       <a href="https://fr.linkedin.com/in/electron-rare" target="_blank" rel="noopener" class="hdr-link hdr-social" title="LinkedIn">in</a>
       <a href="https://github.com/electron-rare/" target="_blank" rel="noopener" class="hdr-link hdr-social" title="GitHub">gh</a>
+      <a href="https://mastodon.saillant.cc/@clement" target="_blank" rel="me noopener" class="hdr-link hdr-social" title="Mastodon">mt</a>
       <a href="https://www.lelectronrare.fr/" class="hdr-link" style="opacity:0.4">Site →</a>
       <a href="https://www.lelectronrare.fr/#contact" class="hdr-cta">Contact</a>
     </nav>