Adds docs/install.html — a visually polished, bilingual (EN/DE)
installation guide matching the index.html design system. Features
step-by-step layout with numbered steps, copy buttons, tabbed
Option A/B install paths, troubleshooting accordion, and dark mode
support.
Updates docs/index.html with a secondary "Installation Guide" CTA
in the hero section and updated setup-note link pointing to the
new page instead of the raw GitHub markdown file.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Ulas Kalayci