Update README files with correct namespaces and usage

Updated code examples in all README files to use the correct Zetian.Server and related namespaces. Added missing using statements for clarity and improved documentation for advanced configuration, message storage, mailbox filtering, and composite filters. This enhances developer experience and ensures examples are accurate and ready to use.

Author: Taiizor

README.md

@@ -44,7 +44,7 @@ Install-Package Zetian
 ### Basic SMTP Server
 
 ```csharp
-using Zetian;
+using Zetian.Server;
 
 // Create and start a basic SMTP server
 using var server = SmtpServerBuilder.CreateBasic();
@@ -66,6 +66,8 @@ await server.StopAsync();
 ### Authenticated SMTP Server
 
 ```csharp
+using Zetian.Server;
+
 using var server = new SmtpServerBuilder()
     .Port(587)
     .RequireAuthentication()
@@ -79,6 +81,8 @@ await server.StartAsync();
 ### Secure SMTP Server with TLS
 
 ```csharp
+using Zetian.Server;
+
 using var server = new SmtpServerBuilder()
     .Port(587)
     .Certificate("certificate.pfx", "password")
@@ -93,6 +97,10 @@ await server.StartAsync();
 ### Using the Fluent Builder
 
 ```csharp
+using System.Net;
+using Zetian.Models;
+using Zetian.Server;
+
 var server = new SmtpServerBuilder()
     .Port(587)
     .BindTo(IPAddress.Any)
@@ -139,8 +147,8 @@ var server = new SmtpServerBuilder()
 ### Rate Limiting
 
 ```csharp
+using Zetian.Models;
 using Zetian.Extensions;
-using Zetian.Extensions.RateLimiting;
 
 server.AddRateLimiting(
     RateLimitConfiguration.PerHour(100)
@@ -276,6 +284,9 @@ server.ErrorOccurred += (s, e) =>
 
 ```csharp
 // Option 1: Create a custom authenticator class
+using Zetian.Models;
+using Zetian.Abstractions;
+
 public class CustomAuthenticator : IAuthenticator
 {
     public string Mechanism => "CUSTOM";
@@ -297,6 +308,9 @@ AuthenticatorFactory.Register("CUSTOM", () =>
     new CustomAuthenticator());
 
 // Option 2: Use the authentication handler with builder
+using Zetian.Models;
+using Zetian.Server;
+
 var server = new SmtpServerBuilder()
     .Port(587)
     .RequireAuthentication()

src/Zetian.HealthCheck/README.MD

@@ -32,7 +32,7 @@ dotnet add package Zetian.HealthCheck
 ### Basic Health Check
 
 ```csharp
-using Zetian;
+using Zetian.Server;
 using Zetian.HealthCheck.Extensions;
 
 // Create and start SMTP server
@@ -87,6 +87,10 @@ var healthCheck = server.EnableHealthCheck(IPAddress.Parse("192.168.1.100"), 808
 ### Custom Health Checks
 
 ```csharp
+using Zetian.Server;
+using Zetian.HealthCheck.Models;
+using Zetian.HealthCheck.Extensions;
+
 var healthCheck = server.EnableHealthCheck(8080);
 
 // Add database check
@@ -132,6 +136,10 @@ await healthCheck.StartAsync();
 ### Advanced Options
 
 ```csharp
+using Zetian.Server;
+using Zetian.HealthCheck.Options;
+using Zetian.HealthCheck.Extensions;
+
 // Custom thresholds for SMTP health
 var smtpOptions = new SmtpHealthCheckOptions
 {
@@ -320,6 +328,8 @@ services:
 ### Prometheus Metrics
 
 ```csharp
+using Zetian.HealthCheck.Models;
+
 // Add custom metrics check for Prometheus
 healthCheck.AddHealthCheck("metrics", async (ct) =>
 {