feat: add complex user invitation and management features

- Implemented complex member and invitation schemas using Zod for validation.
- Created new API endpoints for inviting, accepting, revoking, and canceling complex user invitations.
- Developed handlers for managing complex users, including listing, inviting, revoking, and canceling invitations.
- Added frontend components for displaying and managing complex users and invitations.
- Introduced session storage management for pending invitations.
- Integrated Gravatar for user avatars based on email.
- Created database migration for complex invitations table.

apps/backend/src/generated/prisma/browser.ts

@@ -47,6 +47,11 @@ export type Complex = Prisma.ComplexModel
  * 
  */
 export type ComplexUser = Prisma.ComplexUserModel
+/**
+ * Model ComplexInvitation
+ * 
+ */
+export type ComplexInvitation = Prisma.ComplexInvitationModel
 /**
  * Model Sport
  *