Make TypeCheck setup seamless for Discord server managers

[CompleteDotTech]

Members with Discord Manage Server can install TypeCheck but previously could not sign in or complete setup without Administrator or a separate TypeCheck role grant. Use the same live Discord authority for installation and TypeCheck management.

• Derive Manage Server from Discord's live guild permission bits and expose it separately from the actual Administrator flag.
• Grant the existing management capabilities automatically to owners, Administrators and Manage Server members across Activity/browser sign-in, onboarding, settings, packs and scans. Other members retain explicit role delegation.
• Recheck authority on requests and browser-tool calls; reject client-supplied authority and stop management after revocation. Keep moderation-target protections, review/acceptance requirements and enforcement defaults unchanged.
• Update setup guidance and the checksum manifest. This needs no database migration, new OAuth scope, Discord role creation, or Manage Roles permission.

Validation: production build and all 379 local tests passed. Both push and PR MySQL/full validation jobs passed on final head a8d5f9e. Discord timeouts are included in the live Manage Server check. Tests cover a non-Administrator manager signing in through both entry points without a grant, setup completion, revocation, guild isolation, forged claims and unchanged delegated access. No live Discord acceptance or production deployment is claimed.