Remove login/auth functionality from the web

[manuelgeek]

Remove login / auth functionality from the web

Mirror of the same change in droidconKE/droidconKE2022Web — the repos share the auth stack.

We're dropping user accounts on the site — reviews/feedback are going anonymous. The backend already supports anonymous feedback (endpoints are public and store anonymously); see droidconKE/droidconEventsBanckend#109. Remove the whole login/auth stack from the web.

Remove

• context/AuthContext.tsx (AuthProvider / useAuth) and the AuthProvider wrap in components/layouts/default.tsx
• components/auth/Login.tsx + its modal usage
• GoogleOAuthProvider, the @react-oauth/google dependency, and NEXT_PUBLIC_GOOGLE_CLIENT_ID
• Login / user dropdown in components/layouts/components/NavBar.tsx
• Auth token persistence (localStorage) + any Authorization headers on API calls

Adjust

• Session & event feedback (pages/sessions/[slug].tsx, pages/sessions/index.tsx, EventFeedback) → submit anonymously, no token. BE endpoints already accept this.
• hooks/useStarSession.ts / session bookmarking — currently auth-gated (BE /bookmark_schedule requires auth:sanctum). Decide with BE (#109): remove the star/bookmark feature, or move it to local storage.
• NotificationsPrompt and any UI gated on auth / NEXT_PUBLIC_EVENT_READY login state
• Tidy env/config: drop Google client id and auth-only vars

Acceptance

• No login UI anywhere; feedback can be submitted without an account; no auth tokens stored; build passes with the OAuth dep removed.

Depends on

• droidconKE/droidconEventsBanckend#109 (finalize anonymous reviews/feedback)

cc @NewtonMutugi