05/31 Fix teller webhook endpoint

app/routes/teller.py

@@ -262,7 +262,7 @@ def disconnect(enrollment_db_id):
 
 # ── Webhook: transactions.processed ──────────────────────────────────────────
 
-@teller_bp.route('/webhook', methods=['POST'])
+@teller_bp.route('/webhook', methods=['GET', 'POST'])
 @_csrf.exempt
 def webhook():
     """
@@ -280,6 +280,10 @@ def webhook():
             log.warning('[teller] webhook signature mismatch')
             return jsonify({'error': 'Invalid signature'}), 401
 
+    # Teller sends GET to verify the endpoint is reachable
+    if request.method == 'GET':
+        return jsonify({'status': 'ok', 'service': 'pfm-teller-webhook'}), 200
+
     payload = request.get_json()
     if not payload:
         return jsonify({'error': 'No payload'}), 400
@@ -294,4 +298,4 @@ def webhook():
             # Just log — user syncs manually via UI preview flow
             log.info(f'[teller] new transactions available for enrollment {enrollment_id}')
 
-    return jsonify({'status': 'received'}), 200
+    return jsonify({'status': 'received'}), 200