feat(posts,user): add post CRUD, category ops, token auth, admin guards

[sudipsharma826]

Summary

Add full post CRUD with category operations, update auth (signup/signin) to use token-based flows, enforce admin-only access for post management, standardize schema naming to camelCase, add [GraphQLContext] for cookie handling with type safety, and reorganize types/schema folders.

Changes:

• Add post routes with full CRUD and category operations
• Update auth routes: signup, signin, and token handling
• Rename schema fields to camelCase
• Add admin guard middleware for post routes
• Update auth guard to support token-based auth
• Add GraphQLContext type to handle cookies from GraphQL safely
• Add resolver fields to load related data via foreign keys
• Reorganize types and schema folders
• Handle authentication using email and password