feat: complete release readiness work

- consolidate API ownership and remove dead vendor code

- add Stripe billing, learning paths, and public CV hardening

- add migration, recovery, security, audit, and browser gates

JobTrackerApi/Models/Attachments.cs

@@ -0,0 +1,21 @@
+using System;
+using System.Text.Json.Serialization;
+
+namespace JobTrackerApi.Models
+{
+    public class Attachment
+    {
+        public int Id { get; set; }
+        public int JobApplicationId { get; set; }
+
+        [JsonIgnore]
+        public JobApplication JobApplication { get; set; } = null!;
+        public string FileName { get; set; } = "";
+        public string FilePath { get; set; } = "";
+        public DateTime UploadDate { get; set; } = DateTime.Now;
+        public string FileType { get; set; } = ""; // e.g., PDF, DOCX
+        public long FileSize { get; set; }
+        public string? Purpose { get; set; }
+        public bool UseForAi { get; set; } = true;
+    }
+}