feat: 入库新增「送货日期」字段(与业务日期区分)

- models.Inbound 增加 delivery_date 列(可空, 默认 None)
- 入库单笔录入表单新增「送货日期」输入(默认当天, 可改供应商实际到货日); 出库不受影响
- 物料明细页入库流水新增「送货日期」列展示
- seed_admin 增加幂等补列: 旧库启动时自动 ALTER TABLE inbound ADD COLUMN delivery_date, 开发/EXE 均兼容
- 教程补充送货日期字段说明

(注: instance/app.db 已本地补列, 但未纳入本次提交; dist/app.db 为运行库已 gitignore)

app.py

@@ -430,11 +430,14 @@ def inbound():
         if qty <= 0:
             flash("入库数量必须大于 0", "error")
         else:
+            dlv = request.form.get("delivery_date", "").strip()
+            delivery_date = _date(dlv) if dlv else None
             rec = Inbound(
                 material_id=mid, batch_no=request.form.get("batch_no", ""),
                 qty=qty, operator=request.form.get("operator", ""),
                 source=request.form.get("source", ""),
                 occur_date=_date(request.form.get("occur_date")),
+                delivery_date=delivery_date,
                 remark=request.form.get("remark", ""))
             db.session.add(rec)
             db.session.commit()
@@ -1009,6 +1012,15 @@ def api_import_boms_commit():
 def seed_admin():
     with app.app_context():
         db.create_all()
+        # 兼容旧库: 给 inbound 表补充 delivery_date 列(幂等)
+        try:
+            cols = [r[1] for r in db.session.execute(
+                db.text("PRAGMA table_info(inbound)")).fetchall()]
+            if "delivery_date" not in cols:
+                db.session.execute(db.text("ALTER TABLE inbound ADD COLUMN delivery_date DATE"))
+                db.session.commit()
+        except Exception:
+            db.session.rollback()
         if not db.session.scalar(db.select(User).where(User.username == "admin")):
             db.session.add(User(username="admin", password=sha256("admin123"),
                                 role="admin", display_name="管理员"))