remove dead UploadBundle code and fix Lenovo model detection

- Remove UploadBundleRequest, UploadBundleResponse classes (ApiModels.cs)
- Remove UploadBundle API endpoint constant (Constants.cs)
- Remove GetBundleUploadUrlAsync method (BackendApiClient.cs) — no callers anywhere
- Fix HardwareInfo: Lenovo devices report the marketing model name in
  Win32_ComputerSystemProduct.Version, not Win32_ComputerSystem.Model;
  add Lenovo-specific WMI fallback for correct model string

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/Agent/AutopilotMonitor.Agent.Core/Monitoring/Network/BackendApiClient.cs

@@ -135,16 +135,6 @@ namespace AutopilotMonitor.Agent.Core.Monitoring.Network
             return result;
         }
 
-        /// <summary>
-        /// Gets a SAS URL for uploading a troubleshooting bundle
-        /// </summary>
-        public async Task<UploadBundleResponse> GetBundleUploadUrlAsync(UploadBundleRequest request)
-        {
-            var url = $"{_baseUrl}{Constants.ApiEndpoints.UploadBundle}";
-            var response = await PostAsync<UploadBundleRequest, UploadBundleResponse>(url, request);
-            return response;
-        }
-
         /// <summary>
         /// Requests a short-lived SAS URL for diagnostics package upload.
         /// Called just before upload so the URL is never stored in config or on disk.

src/Shared/AutopilotMonitor.Shared/Constants.cs

@@ -69,8 +69,7 @@ namespace AutopilotMonitor.Shared
         {
             public const string RegisterSession          = "/api/sessions/register";
             public const string IngestEvents             = "/api/events/ingest";
-            public const string UploadBundle             = "/api/bundles/upload";
-            public const string GetAgentConfig           = "/api/agent/config";
+public const string GetAgentConfig           = "/api/agent/config";
             public const string GatherRules              = "/api/gather-rules";
             public const string AnalyzeRules             = "/api/analyze-rules";
             public const string GetDiagnosticsUploadUrl  = "/api/diagnostics/upload-url";

src/Shared/AutopilotMonitor.Shared/Models/ApiModels.cs

@@ -86,28 +86,6 @@ namespace AutopilotMonitor.Shared.Models
         public int RetryAfterSeconds { get; set; }
     }
 
-    /// <summary>
-    /// Request to upload a troubleshooting bundle
-    /// </summary>
-    public class UploadBundleRequest
-    {
-        public string SessionId { get; set; }
-        public string TenantId { get; set; }
-        public string BundleFileName { get; set; }
-    }
-
-    /// <summary>
-    /// Response with SAS URL for bundle upload
-    /// </summary>
-    public class UploadBundleResponse
-    {
-        public bool Success { get; set; }
-        public string SasUrl { get; set; }
-        public string BlobPath { get; set; }
-        public DateTime ExpiresAt { get; set; }
-        public string Message { get; set; }
-    }
-
     /// <summary>
     /// Request to get a short-lived SAS URL for diagnostics package upload.
     /// Called by the agent just before upload — the URL is never cached in config.