fix(types): Add custom Express request types for station authentication

src/types/express.d.ts

@@ -0,0 +1,8 @@
+declare namespace Express {
+    interface Request {
+        /** Set by ScanAuth when the request was authenticated via a station token. Not a header — not spoofable by clients. */
+        isStationAuth?: boolean;
+        /** The authenticated station's DB id. Only present when isStationAuth === true. */
+        stationId?: number;
+    }
+}