feat: enrich gmail correspondence metadata

Models/Correspondence.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Text.Json.Serialization;
 
 namespace JobTrackerApi.Models
@@ -11,13 +12,35 @@ namespace JobTrackerApi.Models
         [JsonIgnore]
         public JobApplication JobApplication { get; set; } = null!;
         public string From { get; set; } = ""; // "Me" or "Company"
+        public string? Direction { get; set; } // inbound, outbound, internal, unknown
         public string? Subject { get; set; }
         public string? Channel { get; set; } // e.g. Email, Call, Note
         public string? ExternalMessageId { get; set; }
         public string? ExternalThreadId { get; set; }
         public string? ExternalFrom { get; set; }
         public string? ExternalTo { get; set; }
+        public string? ExternalLabelsJson { get; set; }
+        public string? AttachmentMetadataJson { get; set; }
         public string Content { get; set; } = "";
         public DateTime Date { get; set; } = DateTime.Now;
+
+        [JsonIgnore]
+        public IReadOnlyList<string> ExternalLabels => string.IsNullOrWhiteSpace(ExternalLabelsJson)
+            ? Array.Empty<string>()
+            : (System.Text.Json.JsonSerializer.Deserialize<List<string>>(ExternalLabelsJson) ?? new List<string>());
+
+        [JsonIgnore]
+        public IReadOnlyList<CorrespondenceAttachmentMetadata> AttachmentMetadata => string.IsNullOrWhiteSpace(AttachmentMetadataJson)
+            ? Array.Empty<CorrespondenceAttachmentMetadata>()
+            : (System.Text.Json.JsonSerializer.Deserialize<List<CorrespondenceAttachmentMetadata>>(AttachmentMetadataJson) ?? new List<CorrespondenceAttachmentMetadata>());
+    }
+
+    public sealed class CorrespondenceAttachmentMetadata
+    {
+        public string? FileName { get; set; }
+        public string? MimeType { get; set; }
+        public long? SizeBytes { get; set; }
+        public string? GmailAttachmentId { get; set; }
+        public bool Inline { get; set; }
     }
 }