feat: 新增退款管理模块 — 完整的退款审批流程、佣金回扣和资产重置

新增退款申请全生命周期管理：创建/列表/详情/审批通过/拒绝/退回/重新提交
审批通过后异步执行佣金全额回扣（扣减各代理佣金钱包）和资产重置（套餐失效+停机+世代重置）
新增 tb_refund_request 表（迁移 000093）、RefundRequest Model、8 个 DTO
新增 Store/Service/Handler/路由注册，仅平台用户可访问

migrations/000093_create_refund_request.up.sql

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+-- 创建退款申请表
+CREATE TABLE IF NOT EXISTS tb_refund_request (
+    id BIGSERIAL PRIMARY KEY,
+    created_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    updated_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    deleted_at TIMESTAMP WITH TIME ZONE,
+    creator BIGINT NOT NULL DEFAULT 0,
+    updater BIGINT NOT NULL DEFAULT 0,
+
+    -- 退款单基础信息
+    refund_no VARCHAR(50) NOT NULL,
+    order_id BIGINT NOT NULL,
+    package_usage_id BIGINT,
+    shop_id BIGINT,
+
+    -- 金额信息
+    actual_received_amount BIGINT NOT NULL,
+    requested_refund_amount BIGINT NOT NULL,
+    approved_refund_amount BIGINT,
+
+    -- 退款原因和状态
+    refund_reason TEXT,
+    status INT NOT NULL DEFAULT 1,
+
+    -- 审批信息
+    processor_id BIGINT,
+    processed_at TIMESTAMP WITH TIME ZONE,
+    reject_reason TEXT,
+    remark TEXT,
+
+    -- 后处理标记
+    commission_deducted BOOLEAN NOT NULL DEFAULT FALSE,
+    asset_reset BOOLEAN NOT NULL DEFAULT FALSE
+);
+
+-- 索引
+CREATE UNIQUE INDEX idx_refund_request_refund_no ON tb_refund_request (refund_no) WHERE deleted_at IS NULL;
+CREATE INDEX idx_refund_request_order_id ON tb_refund_request (order_id);
+CREATE INDEX idx_refund_request_shop_id ON tb_refund_request (shop_id);
+CREATE INDEX idx_refund_request_status ON tb_refund_request (status);
+CREATE INDEX idx_refund_request_deleted_at ON tb_refund_request (deleted_at);
+
+-- 字段注释
+COMMENT ON TABLE tb_refund_request IS '退款申请表';
+COMMENT ON COLUMN tb_refund_request.refund_no IS '退款单号（RF+日期时间+6位随机数）';
+COMMENT ON COLUMN tb_refund_request.order_id IS '关联订单ID';
+COMMENT ON COLUMN tb_refund_request.package_usage_id IS '关联套餐使用记录ID（可选）';
+COMMENT ON COLUMN tb_refund_request.shop_id IS '店铺ID（从订单获取，用于数据权限过滤）';
+COMMENT ON COLUMN tb_refund_request.actual_received_amount IS '实收金额（分）';
+COMMENT ON COLUMN tb_refund_request.requested_refund_amount IS '申请退款金额（分）';
+COMMENT ON COLUMN tb_refund_request.approved_refund_amount IS '审批实际退款金额（分）';
+COMMENT ON COLUMN tb_refund_request.refund_reason IS '退款原因';
+COMMENT ON COLUMN tb_refund_request.status IS '状态 1-待审批 2-已通过 3-已拒绝 4-已退回';
+COMMENT ON COLUMN tb_refund_request.processor_id IS '审批人ID';
+COMMENT ON COLUMN tb_refund_request.processed_at IS '审批时间';
+COMMENT ON COLUMN tb_refund_request.reject_reason IS '拒绝原因';
+COMMENT ON COLUMN tb_refund_request.remark IS '审批备注';
+COMMENT ON COLUMN tb_refund_request.commission_deducted IS '佣金是否已回扣';
+COMMENT ON COLUMN tb_refund_request.asset_reset IS '资产是否已重置（套餐停用+停机+世代重置）';