feat(docs): add docs.atproto.eu organizer handbook (Starlight) master
New Astro + Starlight docs site in docs/, published to the atprotoeu-docs-website Codeberg Pages repo from the Spindle CI as a 13th build target. - Event blueprints (hackathon, meetup, unconference), EU-generic - Getting started, translations, report-a-bug, request-a-feature - Verification (points to hello.mu.social/verification), code of conduct - CONTRIBUTING.md style contract + advisory readability report (npm run check:readability), wired as a non-blocking CI step Retire the old NL-flavoured /events/*.md guides, Guide.astro, and the per-scope events-HTML patch in astro.config.mjs. National events pages now deep-link the handbook. Drop the a11y probe for the removed /events/hackathon route.