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/AccountPlans.cs

@@ -0,0 +1,17 @@
+namespace JobTrackerApi.Models;
+
+public sealed record AccountEntitlements(bool AdvancedAi, bool PremiumThemes, bool Automation, bool Analytics, long StorageBytes, int MonthlyAiCalls, long MonthlyAiTokens);
+
+public static class AccountPlans
+{
+    public static bool IsPremiumSubscriptionStatus(string? status) =>
+        status is "active" or "trialing";
+
+    public static AccountEntitlements ForRoles(IList<string> roles)
+    {
+        var premium = roles.Contains("Premium", StringComparer.OrdinalIgnoreCase) || roles.Contains("Admin", StringComparer.OrdinalIgnoreCase);
+        return premium
+            ? new AccountEntitlements(true, true, true, true, 5_000_000_000, 250, 1_000_000)
+            : new AccountEntitlements(false, false, false, false, 250_000_000, 25, 100_000);
+    }
+}