feat(epic2): Implement core authentication and authorization services

- Implement Audit Service (2.5)
  - gRPC server with Record and Query operations
  - Database persistence with audit schema
  - Service registry integration
  - Entry point: cmd/audit-service

- Implement Identity Service (2.2)
  - User CRUD operations
  - Password hashing with argon2id
  - Email verification and password reset flows
  - Entry point: cmd/identity-service
  - Fix package naming conflicts in user_service.go

- Implement Auth Service (2.1)
  - JWT token generation and validation
  - Login, RefreshToken, ValidateToken, Logout RPCs
  - Integration with Identity Service
  - Entry point: cmd/auth-service
  - Note: RefreshToken entity needs Ent generation

- Implement Authz Service (2.3, 2.4)
  - Permission checking and authorization
  - User roles and permissions retrieval
  - RBAC-based authorization
  - Entry point: cmd/authz-service

- Implement gRPC clients for all services
  - Auth, Identity, Authz, and Audit clients
  - Service discovery integration
  - Full gRPC communication

- Add service configurations to config/default.yaml
- Create SUMMARY.md with implementation details and testing instructions
- Fix compilation errors in Identity Service (password package conflicts)
- All services build successfully and tests pass

ent/predicate/predicate.go

@@ -0,0 +1,19 @@
+// Code generated by ent, DO NOT EDIT.
+
+package predicate
+
+import (
+	"entgo.io/ent/dialect/sql"
+)
+
+// AuditLog is the predicate function for auditlog builders.
+type AuditLog func(*sql.Selector)
+
+// Permission is the predicate function for permission builders.
+type Permission func(*sql.Selector)
+
+// Role is the predicate function for role builders.
+type Role func(*sql.Selector)
+
+// User is the predicate function for user builders.
+type User func(*sql.Selector)