feat: share image, metadata and icons that match the new site

The link preview used an old template with a blog description. The share
image is now a screenshot of the real hero (scripts/render-share-image.mjs),
served as Open Graph and Twitter image. Title and description come from one
place and are used by the page, the previews and the structured data. Adds an
apple touch icon and removes the old share-image template and its fonts.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CLAUDE.md

@@ -28,6 +28,9 @@ App lives in `apps/web`. Concept and scope: `apps/web/plans/freelance-relaunch.m
 - One page: everything lives on the homepage. The header has only "Get in touch", which jumps to the contact
   section (`#contact`). Contact is one email address: no calendar integration, no form. The only other
   pages are `/imprint` and `/privacy`. URLs of the previous site redirect to `/` (see `next.config.mjs`).
+- Title, description and link previews come from `SITE_TITLE` and `SITE_DESCRIPTION` in `src/content/site.ts`.
+  The share image is a screenshot of the real hero: after changing the hero headline or its design, run
+  `pnpm --filter @mintel/web share-image` and commit the two PNGs in `app/(site)/`.
 - The email address is kept in parts (`src/content/site.ts`) and assembled in the browser by `EmailLink`.
   Never write the full address into markup, metadata or copy.
 - The hero design (binary-digit headline) is approved: do not change its design.