Make controller Async

This PR has a large blast radius because it takes the final step and bumps up the Controller to be fully async.

We have historically done a piece-by-piece update, so all operations were already async but the controller interface was kept synchronous.

With this update, the controller is now fully async and all tests are updated.

Most places where the new C# compiler warns about function names not ending in `Async` were also adressed, giving a massive refactor change.

Functionally, no changes are done.

WebserverCore.Client.UsageExample/Program.cs

@@ -37,22 +37,22 @@ class Program
         try
         {
             // Authenticate explicitly (optional - happens automatically on first API call)
-            await client.Authenticate();
+            await client.AuthenticateAsync();
             Console.WriteLine("✓ Authentication successful");
 
             // Demonstrate all client methods
-            await DemonstrateAuthenticationMethods(client);
-            await DemonstrateBackupManagement(client);
-            await DemonstrateBackupOperations(client);
-            await DemonstrateBackupDataAccess(client);
-            await DemonstrateDatabaseManagement(client);
-            await DemonstrateExportOperations(client);
-            await DemonstrateServerManagement(client);
-            await DemonstrateTaskManagement(client);
-            await DemonstrateSystemInformation(client);
-            await DemonstrateSettingsManagement(client);
-            await DemonstrateFilesystemOperations(client);
-            await DemonstrateV2ApiMethods(client);
+            await DemonstrateAuthenticationMethodsAsync(client);
+            await DemonstrateBackupManagementAsync(client);
+            await DemonstrateBackupOperationsAsync(client);
+            await DemonstrateBackupDataAccessAsync(client);
+            await DemonstrateDatabaseManagementAsync(client);
+            await DemonstrateExportOperationsAsync(client);
+            await DemonstrateServerManagementAsync(client);
+            await DemonstrateTaskManagementAsync(client);
+            await DemonstrateSystemInformationAsync(client);
+            await DemonstrateSettingsManagementAsync(client);
+            await DemonstrateFilesystemOperationsAsync(client);
+            await DemonstrateV2ApiMethodsAsync(client);
         }
         catch (Exception ex)
         {
@@ -63,7 +63,7 @@ class Program
     /// <summary>
     /// Demonstrates authentication-related methods
     /// </summary>
-    static async Task DemonstrateAuthenticationMethods(DuplicatiServerClient client)
+    static async Task DemonstrateAuthenticationMethodsAsync(DuplicatiServerClient client)
     {
         Console.WriteLine("\n=== Authentication Methods ===");
 
@@ -78,7 +78,7 @@ class Program
             var operationToken = await client.IssueTokenV1Async("export", CancellationToken.None);
             Console.WriteLine($"✓ Operation token issued: {operationToken.Token[..10]}...");
 
-            await client.Authenticate();
+            await client.AuthenticateAsync();
             // Issue a forever token
             try
             {
@@ -110,7 +110,7 @@ class Program
     /// <summary>
     /// Demonstrates backup management methods
     /// </summary>
-    static async Task DemonstrateBackupManagement(DuplicatiServerClient client)
+    static async Task DemonstrateBackupManagementAsync(DuplicatiServerClient client)
     {
         Console.WriteLine("\n=== Backup Management ===");
 
@@ -181,7 +181,7 @@ class Program
     /// <summary>
     /// Demonstrates backup operations
     /// </summary>
-    static async Task DemonstrateBackupOperations(DuplicatiServerClient client)
+    static async Task DemonstrateBackupOperationsAsync(DuplicatiServerClient client)
     {
         Console.WriteLine("\n=== Backup Operations ===");
 
@@ -248,7 +248,7 @@ class Program
     /// <summary>
     /// Demonstrates backup data access methods
     /// </summary>
-    static async Task DemonstrateBackupDataAccess(DuplicatiServerClient client)
+    static async Task DemonstrateBackupDataAccessAsync(DuplicatiServerClient client)
     {
         Console.WriteLine("\n=== Backup Data Access ===");
 
@@ -289,7 +289,7 @@ class Program
     /// <summary>
     /// Demonstrates database management methods
     /// </summary>
-    static async Task DemonstrateDatabaseManagement(DuplicatiServerClient client)
+    static async Task DemonstrateDatabaseManagementAsync(DuplicatiServerClient client)
     {
         Console.WriteLine("\n=== Database Management ===");
 
@@ -333,7 +333,7 @@ class Program
     /// <summary>
     /// Demonstrates export operations
     /// </summary>
-    static async Task DemonstrateExportOperations(DuplicatiServerClient client)
+    static async Task DemonstrateExportOperationsAsync(DuplicatiServerClient client)
     {
         Console.WriteLine("\n=== Export Operations ===");
 
@@ -371,7 +371,7 @@ class Program
     /// <summary>
     /// Demonstrates server management methods
     /// </summary>
-    static async Task DemonstrateServerManagement(DuplicatiServerClient client)
+    static async Task DemonstrateServerManagementAsync(DuplicatiServerClient client)
     {
         Console.WriteLine("\n=== Server Management ===");
 
@@ -405,7 +405,7 @@ class Program
     /// <summary>
     /// Demonstrates task management methods
     /// </summary>
-    static async Task DemonstrateTaskManagement(DuplicatiServerClient client)
+    static async Task DemonstrateTaskManagementAsync(DuplicatiServerClient client)
     {
         Console.WriteLine("\n=== Task Management ===");
 
@@ -451,7 +451,7 @@ class Program
     /// <summary>
     /// Demonstrates system information methods
     /// </summary>
-    static async Task DemonstrateSystemInformation(DuplicatiServerClient client)
+    static async Task DemonstrateSystemInformationAsync(DuplicatiServerClient client)
     {
         Console.WriteLine("\n=== System Information ===");
 
@@ -488,7 +488,7 @@ class Program
     /// <summary>
     /// Demonstrates settings management methods
     /// </summary>
-    static async Task DemonstrateSettingsManagement(DuplicatiServerClient client)
+    static async Task DemonstrateSettingsManagementAsync(DuplicatiServerClient client)
     {
         Console.WriteLine("\n=== Settings Management ===");
 
@@ -525,7 +525,7 @@ class Program
     /// <summary>
     /// Demonstrates filesystem operations
     /// </summary>
-    static async Task DemonstrateFilesystemOperations(DuplicatiServerClient client)
+    static async Task DemonstrateFilesystemOperationsAsync(DuplicatiServerClient client)
     {
         Console.WriteLine("\n=== Filesystem Operations ===");
 
@@ -559,7 +559,7 @@ class Program
     /// <summary>
     /// Demonstrates V2 API methods
     /// </summary>
-    static async Task DemonstrateV2ApiMethods(DuplicatiServerClient client)
+    static async Task DemonstrateV2ApiMethodsAsync(DuplicatiServerClient client)
     {
         Console.WriteLine("\n=== V2 API Methods ===");