feat: 打通采购申请与入库的按单入库链路

后端变更:
- PurchaseRequest 新增 base_id 硬关联 MaterialBase，StockBuy 新增 request_id 关联采购单
- handle_inbound 支持 request_id 入参，入库后自动反写采购单状态为已完成
- 新增 get_approved_requests 接口，返回已审批未入库采购单列表（含物料信息+历史数据回退匹配）
- create_purchase_request 新增 name+spec_model 自动匹配 MaterialBase
- 新增 SQL 和 Alembic 数据库迁移脚本

前端变更:
- 入库表单新增"从采购单导入"弹窗，支持搜索/选中已审批采购单并一键填充物料和商务信息
- 单价/总价交叉推算，缺项自动补全
- 选中行蓝色高亮+点击整行选中，行级交互优化

inventory-backend/migrations/versions/a1b2c3d4e5f6_add_purchase_stockbuy_link.py

@@ -0,0 +1,79 @@
+"""打通采购申请与采购入库的按单入库链路
+
+Revision ID: a1b2c3d4e5f6
+Revises: None (或填当前最新 revision)
+Create Date: 2026-07-14
+
+变更内容:
+  1. purchase_request 表新增 base_id (FK → material_base.id)
+  2. stock_buy 表新增 request_id (FK → purchase_request.id)
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = 'a1b2c3d4e5f6'
+down_revision = None   # ← 替换为当前最新 revision ID
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # ============================================================
+    # 1. purchase_request 新增 base_id
+    # ============================================================
+    with op.batch_alter_table('purchase_request', schema=None) as batch_op:
+        batch_op.add_column(
+            sa.Column('base_id', sa.Integer(), nullable=True,
+                      comment='关联基础物料ID')
+        )
+        batch_op.create_foreign_key(
+            'fk_purchase_request_base_id',
+            'material_base',
+            ['base_id'],
+            ['id'],
+            ondelete='SET NULL'
+        )
+        batch_op.create_index(
+            'ix_purchase_request_base_id',
+            ['base_id']
+        )
+
+    # ============================================================
+    # 2. stock_buy 新增 request_id
+    # ============================================================
+    with op.batch_alter_table('stock_buy', schema=None) as batch_op:
+        batch_op.add_column(
+            sa.Column('request_id', sa.Integer(), nullable=True,
+                      comment='关联采购申请单ID')
+        )
+        batch_op.create_foreign_key(
+            'fk_stock_buy_request_id',
+            'purchase_request',
+            ['request_id'],
+            ['id'],
+            ondelete='SET NULL'
+        )
+        batch_op.create_index(
+            'ix_stock_buy_request_id',
+            ['request_id']
+        )
+
+
+def downgrade():
+    # ============================================================
+    # 回滚：stock_buy 删除 request_id
+    # ============================================================
+    with op.batch_alter_table('stock_buy', schema=None) as batch_op:
+        batch_op.drop_constraint('fk_stock_buy_request_id', type_='foreignkey')
+        batch_op.drop_index('ix_stock_buy_request_id')
+        batch_op.drop_column('request_id')
+
+    # ============================================================
+    # 回滚：purchase_request 删除 base_id
+    # ============================================================
+    with op.batch_alter_table('purchase_request', schema=None) as batch_op:
+        batch_op.drop_constraint('fk_purchase_request_base_id', type_='foreignkey')
+        batch_op.drop_index('ix_purchase_request_base_id')
+        batch_op.drop_column('base_id')