API: follower lists, blocking, reports, admin; drop Spotify sign-in

- Followers/following lists (paginated), 'follows you', remove a follower
- Blocking severs follows both ways and hides each user from the other
  (profile 404s, search, follows); the blocker sees activity hidden
- Reports for moderation (App Store guideline 1.2)
- First account on a server becomes admin; admins see the report queue,
  resolve reports, and suspend accounts (signs out, blocks login, hides
  the profile, stops sharing). set-role script to promote/demote
- users.onboardedAt drives first-run onboarding; existing accounts are
  backfilled as already onboarded. Empty PATCH /me no longer 500s
- Remove Spotify account sign-in and polling: Spotify caps new apps at 5
  accounts, so Spotify arrives via its Last.fm/ListenBrainz link or the
  Android reader. App-level catalog search stays for exact links
- Shared: QR code generation and profile-link parsing (verified with jsQR)
- Integration test timeout raised; password hashing is slow by design

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MzFywujuH9TiuXbr9vjoX8

apps/api/.env.example

@@ -28,3 +28,10 @@ ALLOW_PRIVATE_SERVER_URLS=false
 APPLE_TEAM_ID=
 APPLE_MUSICKIT_KEY_ID=
 APPLE_MUSICKIT_PRIVATE_KEY=
+
+# Outgoing email (verification, password reset). SMTPS on 465.
+SMTP_HOST=
+SMTP_PORT=465
+SMTP_USER=
+SMTP_PASSWORD=
+MAIL_FROM=musicshare <app@musicshare.binarygnome.com>