build: 打通 FastAPI 与 Vue 最小工程、依赖与数据库连接

后端入口、配置、Redis 与 Alembic 迁移就位；前端 Vite 工程可安装可构建。

backend/alembic/versions/add_ticket_csat.py

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+"""CSAT score linkage on tickets
+
+Revision ID: add_tkt_csat_001
+Revises: add_tkt_row_scope_001
+Create Date: 2026-07-22
+
+The CSAT ask already goes out on close; nothing carried the answer back. These
+columns close the loop: when the customer rates the conversation linked to a
+ticket, the score lands on the ticket itself, so AI-resolved vs human-resolved
+CSAT is a plain query instead of a join through ratings/sessions.
+"""
+from alembic import op
+import sqlalchemy as sa
+
+revision = "add_tkt_csat_001"
+down_revision = "add_tkt_row_scope_001"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.add_column("tickets", sa.Column("csat_requested_at", sa.DateTime(timezone=True), nullable=True))
+    op.add_column("tickets", sa.Column("csat_score", sa.Integer(), nullable=True))
+    op.add_column("tickets", sa.Column("csat_rating_id", sa.UUID(), nullable=True))
+    op.add_column("tickets", sa.Column("csat_responded_at", sa.DateTime(timezone=True), nullable=True))
+    op.create_foreign_key(
+        "fk_tickets_csat_rating_id",
+        "tickets",
+        "ratings",
+        ["csat_rating_id"],
+        ["id"],
+        ondelete="SET NULL",
+    )
+    op.create_index("ix_tickets_org_csat", "tickets", ["organization_id", "csat_responded_at"])
+
+
+def downgrade() -> None:
+    op.drop_index("ix_tickets_org_csat", table_name="tickets")
+    op.drop_constraint("fk_tickets_csat_rating_id", "tickets", type_="foreignkey")
+    op.drop_column("tickets", "csat_responded_at")
+    op.drop_column("tickets", "csat_rating_id")
+    op.drop_column("tickets", "csat_score")
+    op.drop_column("tickets", "csat_requested_at")