Add CRM order queue: live sync, view modal, receipt tabs, delete

Wires the CRM (exoCRM GetOrders) into the dashboard as a locally
persisted order queue instead of the previous static mockup:

- CrmClient Protocol + ExoCrmClient/StubCrmClient for the CRM's
  signed JSON-RPC API
- Order model + migration, synced from CRM on each queue view;
  soft-deleted orders stay hidden across re-syncs
- GET/DELETE /api/v1/orders with "no receipt"/"receipt issued" tabs
  (the latter is empty until Checkbox fiscalization lands)
- Dashboard: real order list, item-detail modal, tab switcher,
  one-click delete

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

backend/app/services/crm/stub_client.py

@@ -0,0 +1,49 @@
+"""Фикстурный CRM-клиент для тестов — не ходит в сеть."""
+
+from __future__ import annotations
+
+from app.schemas.orders import OrderOut
+
+_FIXTURE_ORDERS: list[dict] = [
+    {
+        "ID": "100001",
+        "CreateDateTime": "2026-09-20 10:00:00",
+        "RecipientDName": "Тестовий Покупець",
+        "RecipientPhone": "+380501112233",
+        "RecipientEmail": None,
+        "Waybill_Number": "20450123456789",
+        "Notes": "Тестовий заказ",
+        "Total": {
+            "Cost": "0.00",
+            "Quantity": "2",
+            "Weight": "0",
+            "DiscountAmount": "0.00",
+            "DiscountPercent": "0.00",
+            "Amount": "1200.00",
+        },
+        "Goods": [
+            {
+                "ID": "1",
+                "SKU": "SKU-1",
+                "Name": "Товар 1",
+                "Price": "600.00",
+                "Quantity": "2.000",
+                "DiscountAmount": "0.00",
+                "DiscountPercent": "0.00",
+                "Amount": "1200.00",
+            }
+        ],
+    }
+]
+
+
+class StubCrmClient:
+    def __init__(self, orders: list[dict] | None = None) -> None:
+        self._orders = orders if orders is not None else _FIXTURE_ORDERS
+
+    async def get_orders(self, *, status: str) -> list[OrderOut]:
+        return [
+            OrderOut.model_validate(order)
+            for order in self._orders
+            if order.get("Status", status) == status
+        ]