feat(index): render authed home dashboard
Port the home-page authed branch from atmoquest. - features/index/pages/index.templ: introduce IndexView / IndexEventCard, split into indexAuthed + indexGuest + indexEventCard templ funcs; IndexPage(v) now branches on v.LoggedIn. - features/index/handlers.go: soft-check session cookie via h.Auth.Sessions.Get (no OAuth resume — home is public). When logged in, enrich with bsky display name + avatar, /profile/qr.svg, and the user's current ongoing event via checkin.Current + event.Get. Resolve handle via identity.DefaultDirectory with shortDIDLabel fallback. Each step soft-fails to slog.Debug so a Bluesky outage / empty event cache never 500s home. - features/index/routes.go + router/router.go: thread *auth.Handlers into index.SetupRoutes. Build clean, all tests pass, GET / (anon) renders the guest landing unchanged (verified via curl localhost:9090).