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/GmailConnection.cs

@@ -0,0 +1,20 @@
+namespace JobTrackerApi.Models;
+
+public sealed class GmailConnection
+{
+    public int Id { get; set; }
+    public string OwnerUserId { get; set; } = "";
+    public string GmailAddress { get; set; } = "";
+    public string EncryptedRefreshToken { get; set; } = "";
+    public string? EncryptedAccessToken { get; set; }
+    public DateTimeOffset? AccessTokenExpiresAt { get; set; }
+    public string Scope { get; set; } = "";
+    public DateTimeOffset ConnectedAt { get; set; } = DateTimeOffset.UtcNow;
+    public DateTimeOffset? LastSyncedAt { get; set; }
+    public DateTimeOffset? LastSyncAttemptedAt { get; set; }
+    public DateTimeOffset? LastSyncSucceededAt { get; set; }
+    public string? LastSyncMode { get; set; }
+    public string? LastSyncSource { get; set; }
+    public string? LastSyncStatus { get; set; }
+    public string? LastSyncError { get; set; }
+}