feat(deploy): 完成数据迁移与MySQL全链路(14表698k消息100%一致+5方言补丁+bind mount)

- migrate_sqlite_to_mysql.py: 逐表清空重导(幂等),复用repos强转,JSON列
  解析,67万消息按msg_id键集分批,467s跑完14表全一致
- 修4个MySQL实测bug: NULLS LAST语法(compat.py编译补丁)、message.text
  TEXT→MEDIUMTEXT(64KB字节上限,实测20.8万字符车源清单)、URL列
  String(1024)→Text(分享链接超1KB)、垃圾超长member_id源头清理
- compose: media改bind mount(不占C盘Docker虚拟磁盘,实测2.5GB卷把
  C盘撑爆引擎500);mysql不映射宿主机3306
- 前端Dockerfile: npm ci→install(本地/容器npm版本锁漂移)
- 五服务实测:nginx→backend→MySQL全链路返回真实数据(客户6859/A**杰25条
  /搜索56条),媒体49536文件bind mount直读

Co-Authored-By: Claude <noreply@anthropic.com>

yunke-server/app/db/models.py

@@ -45,6 +45,7 @@ import datetime as dt
 from typing import Any
 
 import sqlalchemy as sa
+from sqlalchemy.dialects.mysql import MEDIUMTEXT  # noqa: E402
 from sqlalchemy import BigInteger, Boolean, DateTime, Index, Integer, String, Text
 from sqlalchemy.orm import Mapped, mapped_column
 from sqlalchemy.types import JSON
@@ -358,10 +359,14 @@ class Message(Base):
     type_raw: Mapped[int | None] = mapped_column(
         Integer, nullable=True
     )  # original upstream type code (e.g. WeChat 1=text, -2=divider)
-    text: Mapped[str | None] = mapped_column(Text, nullable=True)  # content/text
-    file_url: Mapped[str | None] = mapped_column(String(1024), nullable=True)
-    file_th_url: Mapped[str | None] = mapped_column(String(1024), nullable=True)
-    file_hd_url: Mapped[str | None] = mapped_column(String(1024), nullable=True)
+    # MEDIUMTEXT(16MB):MySQL TEXT 上限 64KB 字节,实测车源清单消息最长
+    # 20.8万字符(≈800KB utf8mb4)超限(2026-08-21 迁移踩坑)
+    text: Mapped[str | None] = mapped_column(
+        Text().with_variant(MEDIUMTEXT(), "mysql"), nullable=True
+    )  # content/text
+    file_url: Mapped[str | None] = mapped_column(sa.Text, nullable=True)  # 分享链接可超1KB(实测,2026-08-21)
+    file_th_url: Mapped[str | None] = mapped_column(sa.Text, nullable=True)
+    file_hd_url: Mapped[str | None] = mapped_column(sa.Text, nullable=True)
     md5: Mapped[str | None] = mapped_column(String(64), nullable=True)
     md5_th: Mapped[str | None] = mapped_column(String(64), nullable=True)
     md5_hd: Mapped[str | None] = mapped_column(String(64), nullable=True)
@@ -428,7 +433,7 @@ class Media(Base):
     media_type: Mapped[str | None] = mapped_column(
         String(32), nullable=True
     )  # image|voice|video|file|...
-    original_url: Mapped[str | None] = mapped_column(String(1024), nullable=True)
+    original_url: Mapped[str | None] = mapped_column(sa.Text, nullable=True)
     original_th_url: Mapped[str | None] = mapped_column(String(1024), nullable=True)
     original_hd_url: Mapped[str | None] = mapped_column(String(1024), nullable=True)
     local_path: Mapped[str | None] = mapped_column(String(1024), nullable=True)