refactor(auth): simplify authorization checks to use membership only

- Remove explicit ADMIN role checks in API handlers
- Replace combined creator/member role checks with membership-only filters
- Update seed data roles to reflect changed authorization logic
- Add migration to insert hunt creators as members for consistent checks
- Prevent removal of hunt creator as a member with new explicit check
- Adjust related user role updates and queries accordingly
- Upgrade dependencies including nuxt and zod for compatibility

prisma/migrations/20260730000000_add_creators_as_hunt_members/migration.sql

@@ -0,0 +1,8 @@
+-- Add hunt creators as HuntMembers so authorization only needs membership check
+INSERT INTO "HuntMember" ("huntId", "memberId", "createdAt")
+SELECT h."id", h."creatorId", NOW()
+FROM "Hunt" h
+WHERE NOT EXISTS (
+  SELECT 1 FROM "HuntMember" hm
+  WHERE hm."huntId" = h."id" AND hm."memberId" = h."creatorId"
+);