Detect declined sessions (200 + Status:Error); theme Sessions screen

- startParkingSession: server returns HTTP 200 even on a declined charge — now
  detect Response.Status:"Error" and throw the gateway reason (e.g. "DECLINED")
  so the app shows the failure instead of a false "Parked!"
- Confirmed the session request format is correct (server processed it); expand
  StartParkingSessionResponse with the real fields (OriginalErrorMessage, etc.)
- Theme SessionsScreen (was black-on-black in dark mode)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

parksmarter-client/src/client.ts

@@ -598,13 +598,20 @@ export class ParkSmarterClient {
       MeterTypeId: params.meterTypeId,
     };
     if (params.bleEncBytes) body.BleEncBytes = params.bleEncBytes;
-    return this.unwrap(
-      this.http.request<T.StartParkingSessionResponse>({
-        method: 'POST',
-        path: '/api/Session',
-        body,
-      }),
-    );
+    return this.http
+      .request<T.StartParkingSessionResponse>({ method: 'POST', path: '/api/Session', body })
+      .then((res) => {
+        // The server returns HTTP 200 even when the charge is declined, signalling
+        // failure via Response.Status:"Error" (+ OriginalErrorMessage like "DECLINED").
+        const env = res.data?.Response as { Status?: string; Message?: string } | undefined;
+        if (env?.Status === 'Error') {
+          throw new Error(
+            (env.Message || 'Payment failed.') +
+              (res.data?.OriginalErrorMessage ? ` (${res.data.OriginalErrorMessage})` : ''),
+          );
+        }
+        return res.data;
+      });
   }
 
   /** GET /api/ParkingSession — currently active sessions. */

parksmarter-client/src/types.ts

@@ -452,8 +452,29 @@ export interface StartParkingSessionParams {
   bleEncBytes?: string;
 }
 
+/**
+ * POST /api/Session. CONFIRMED via live capture. Returns HTTP 200 even on a
+ * declined charge — check `Response.Status === 'Error'` (the client does this and
+ * throws). `OriginalErrorMessage` carries the gateway reason (e.g. "DECLINED").
+ */
 export interface StartParkingSessionResponse {
-  BleEncBytes?: string;
+  Response?: ResponseEnvelope;
+  BleEncBytes?: string | null;
+  PBPParkingSessionId?: number;
+  OriginalErrorMessage?: string;
+  StartTime?: string | null;
+  EndTime?: string | null;
+  TimePurchased?: string | null;
+  ZoneID?: number | string | null;
+  Zone?: string | null;
+  SpaceID?: number | string | null;
+  Space?: string | null;
+  VehicleNumber?: string | null;
+  Lat?: number | null;
+  Long?: number | null;
+  TransactionFee?: string | number | null;
+  Amount?: string | number | null;
+  AmountCharged?: string | number | null;
   [key: string]: unknown;
 }