TASK 10: Polar billing + Velopack auto-updates (steps 1-7)

Services/LayoutStore.cs

@@ -1027,6 +1027,76 @@ public class LayoutStore : IDisposable
         return (string)cmd.ExecuteScalar()!;
     }
 
+    // ─── License (TASK 10 — Polar billing) ───
+
+    /// <summary>The saved license key, or null if never entered.</summary>
+    public string? LoadLicenseKey()
+    {
+        using var cmd = _connection.CreateCommand();
+        cmd.CommandText = "SELECT Value FROM Settings WHERE Key = 'LicenseKey';";
+        var value = cmd.ExecuteScalar() as string;
+        return string.IsNullOrWhiteSpace(value) ? null : value;
+    }
+
+    public void SaveLicenseKey(string? key)
+    {
+        using var cmd = _connection.CreateCommand();
+        cmd.CommandText = "DELETE FROM Settings WHERE Key = 'LicenseKey';";
+        cmd.ExecuteNonQuery();
+        if (string.IsNullOrWhiteSpace(key)) return;
+
+        using var insert = _connection.CreateCommand();
+        insert.CommandText = "INSERT INTO Settings (Key, Value) VALUES ('LicenseKey', $value);";
+        insert.Parameters.AddWithValue("$value", key);
+        insert.ExecuteNonQuery();
+    }
+
+    /// <summary>When the license was last validated online (ISO 8601), or null if never.</summary>
+    public DateTime? LoadLicenseValidatedAt()
+    {
+        using var cmd = _connection.CreateCommand();
+        cmd.CommandText = "SELECT Value FROM Settings WHERE Key = 'LicenseValidatedAt';";
+        var value = cmd.ExecuteScalar() as string;
+        if (string.IsNullOrWhiteSpace(value)) return null;
+        return DateTime.TryParse(value, out var dt) ? dt : null;
+    }
+
+    public void SaveLicenseValidatedAt(DateTime? dt)
+    {
+        using var cmd = _connection.CreateCommand();
+        cmd.CommandText = "DELETE FROM Settings WHERE Key = 'LicenseValidatedAt';";
+        cmd.ExecuteNonQuery();
+        if (dt == null) return;
+
+        using var insert = _connection.CreateCommand();
+        insert.CommandText = "INSERT INTO Settings (Key, Value) VALUES ('LicenseValidatedAt', $value);";
+        insert.Parameters.AddWithValue("$value", dt.Value.ToString("o"));
+        insert.ExecuteNonQuery();
+    }
+
+    /// <summary>Cached premium state (1 = premium, 0 = free). Used for offline
+    /// grace period — the app checks online at startup but uses this cached
+    /// value when offline.</summary>
+    public bool LoadIsPremium()
+    {
+        using var cmd = _connection.CreateCommand();
+        cmd.CommandText = "SELECT Value FROM Settings WHERE Key = 'IsPremium';";
+        var value = cmd.ExecuteScalar() as string;
+        return value == "1";
+    }
+
+    public void SaveIsPremium(bool isPremium)
+    {
+        using var cmd = _connection.CreateCommand();
+        cmd.CommandText = "DELETE FROM Settings WHERE Key = 'IsPremium';";
+        cmd.ExecuteNonQuery();
+
+        using var insert = _connection.CreateCommand();
+        insert.CommandText = "INSERT INTO Settings (Key, Value) VALUES ('IsPremium', $value);";
+        insert.Parameters.AddWithValue("$value", isPremium ? "1" : "0");
+        insert.ExecuteNonQuery();
+    }
+
     public void Dispose()
     {
         _connection.Dispose();