Allow editing orders in the order card

Cashiers can edit recipient, TTN, notes, goods and total in the order
modal and save via PATCH /orders/{id}. Edited orders get edited_at and
are no longer overwritten by CRM sync. Editing is blocked once a receipt
exists; changing the TTN resets Nova Poshta tracking fields.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

backend/alembic/versions/0007_order_edited_at.py

@@ -0,0 +1,26 @@
+"""Отметка о ручном редактировании заказа
+
+Revision ID: 0007
+Revises: 0006
+Create Date: 2026-09-24
+"""
+
+from __future__ import annotations
+
+from collections.abc import Sequence
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "0007"
+down_revision: str | None = "0006"
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+
+def upgrade() -> None:
+    op.add_column("orders", sa.Column("edited_at", sa.DateTime(timezone=True), nullable=True))
+
+
+def downgrade() -> None:
+    op.drop_column("orders", "edited_at")