feat(hotelGroups): add offer display fields and related logic

- Add new database columns (coverImage, priceAmount, priceUnit, tags, status) to HotelGroup model
- Create hotel_group_dict serializer to handle image/coverImage synchronization and tag formatting
- Update site config endpoints to use the new serializer and filter published hotel groups
- Add Alembic migration for the new database schema changes
- Update test fixtures and API contract tests for the new fields
- Revise public and admin API documentation to document the new hotel group fields and usage rules

alembic/versions/0006_hotel_group_offer_fields.py

@@ -0,0 +1,55 @@
+"""Add offer display fields to hotel groups.
+
+Revision ID: 0006_hotel_group_offer_fields
+Revises: 0005_hotel_vehicle_modules
+Create Date: 2026-07-03
+"""
+
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy import inspect
+from sqlalchemy.dialects import postgresql
+
+
+revision = "0006_hotel_group_offer_fields"
+down_revision = "0005_hotel_vehicle_modules"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    bind = op.get_bind()
+    if "HotelGroup" not in set(inspect(bind).get_table_names()):
+        return
+
+    columns = {column["name"] for column in inspect(bind).get_columns("HotelGroup")}
+    if "coverImage" not in columns:
+        op.add_column("HotelGroup", sa.Column("coverImage", sa.String(), nullable=True))
+        op.execute('UPDATE "HotelGroup" SET "coverImage" = image WHERE "coverImage" IS NULL')
+    if "priceAmount" not in columns:
+        op.add_column("HotelGroup", sa.Column("priceAmount", sa.Integer(), nullable=True))
+    if "priceUnit" not in columns:
+        op.add_column("HotelGroup", sa.Column("priceUnit", sa.String(), nullable=True, server_default="起/晚"))
+    if "tags" not in columns:
+        op.add_column(
+            "HotelGroup",
+            sa.Column(
+                "tags",
+                postgresql.ARRAY(sa.String()),
+                nullable=False,
+                server_default=sa.text("'{}'::varchar[]"),
+            ),
+        )
+    if "status" not in columns:
+        op.add_column("HotelGroup", sa.Column("status", sa.String(), nullable=False, server_default="published"))
+
+
+def downgrade() -> None:
+    bind = op.get_bind()
+    if "HotelGroup" not in set(inspect(bind).get_table_names()):
+        return
+
+    columns = {column["name"] for column in inspect(bind).get_columns("HotelGroup")}
+    for column_name in ["status", "tags", "priceUnit", "priceAmount", "coverImage"]:
+        if column_name in columns:
+            op.drop_column("HotelGroup", column_name)