feat(platform): add Discord onboarding and Velocity gate

.env.example

@@ -3,6 +3,7 @@ APP_URL=http://localhost:3000
 SESSION_SECRET=
 
 # Admin OIDC / Keycloak
+NEXTAUTH_URL=http://localhost:3000
 AUTH_SECRET=
 KEYCLOAK_ISSUER_URL=
 KEYCLOAK_CLIENT_ID=minecraft-account-manager-admin
@@ -12,6 +13,11 @@ KEYCLOAK_REQUIRED_ROLE=minecraft-account-manager-admin
 # Discord
 DISCORD_BOT_TOKEN=
 DISCORD_APPLICATION_ID=
+DISCORD_GUILD_ID=
+DISCORD_INVITE_URL=https://discord.gg/your-invite
+
+# Trust forwarding headers only when your reverse proxy overwrites them
+TRUST_PROXY=false
 
 # Optional VPN intelligence provider (deferred for v1)
 IP_INTELLIGENCE_PROVIDER=none