health: fix broken pages, add image dimensions, a11y & SEO wins

Site-wide health pass (excludes in-progress blog work). Verified with a
local server + headless browser: Timeline, homepage and gallery pages load
with zero console errors and no layout distortion.

Render bugs
- Timeline page (en/mk/si): fix ../../../ paths that overshot the site root,
  so the main stylesheet and hero image load again.
- Meet Student Slovenia 2023 (en/mk/si): remove a <figure> referencing
  event3-photo-11.png, an image that was never uploaded (broken image).

Performance
- Add intrinsic width/height to 1039 raster <img> tags to prevent layout
  shift (CLS); 450 SVGs correctly skipped. Add a global
  `img { max-width:100%; height:auto }` safety net so aspect ratio is
  preserved and images never overflow.
- Preload the homepage hero (LCP) image on en/mk/si.
- Load Font Awesome non-blocking (media=print/onload swap) with a <noscript>
  fallback, on 225 pages.

Accessibility
- Add aria-label to 57 unlabeled newsletter email inputs.
- Add an sr-only <h1> to the three "My Route" pages (had no h1).
- Add an .sr-only utility class.

SEO
- Add meta descriptions to legal/msos-hub/support pages (en/mk/si).

Note: MK/SI meta descriptions are machine-drafted and should be proofread
by a native speaker before considering them final.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

404.html

@@ -50,7 +50,7 @@
 <body>
     <main class="nf-wrap">
         <div class="nf-card">
-            <a href="/en/"><img loading="lazy" decoding="async" src="/images/1-logo.png" alt="Macedonian Student Organisation in Slovenia"></a>
+            <a href="/en/"><img width="604" height="130" loading="lazy" decoding="async" src="/images/1-logo.png" alt="Macedonian Student Organisation in Slovenia"></a>
             <p class="nf-code">404 error</p>
             <h1>Page not found</h1>
             <p class="nf-lead">The page you're looking for doesn't exist or may have moved. Let's get you back on track.</p>