refactor: 迁移脚本系统重构 + 新增 db 脚本 + 工作日志

- 清理全部旧迁移文件(0000-0011)和 meta 目录
- 使用 drizzle-kit generate 从 schema 重新生成单一迁移文件
  - 0000_perfect_pestilence.sql: 包含全部 49 张表
  - 修复 0011_ai_providers.sql 未在 journal 注册导致 migrate 失败的问题
  - 修复缺少 snapshot 文件的问题
  - 移除复杂 PREPARE/EXECUTE 条件 SQL,使用标准 CREATE TABLE
- package.json 新增脚本:
  - db:create: 创建数据库
  - db:push: 直接同步 schema(开发用)
  - db:setup: 一键 create → migrate → seed
- 干净数据库全流程测试通过: create → migrate → seed
- 更新工作日志(docs/work_log.md)

drizzle/meta/_journal.json

@@ -5,79 +5,9 @@
     {
       "idx": 0,
       "version": "5",
-      "when": 1766460456274,
-      "tag": "0000_aberrant_cobalt_man",
-      "breakpoints": true
-    },
-    {
-      "idx": 1,
-      "version": "5",
-      "when": 1767004087964,
-      "tag": "0001_flawless_texas_twister",
-      "breakpoints": true
-    },
-    {
-      "idx": 2,
-      "version": "5",
-      "when": 1767145757594,
-      "tag": "0002_equal_wolfpack",
-      "breakpoints": true
-    },
-    {
-      "idx": 3,
-      "version": "5",
-      "when": 1767166769676,
-      "tag": "0003_petite_newton_destine",
-      "breakpoints": true
-    },
-    {
-      "idx": 4,
-      "version": "5",
-      "when": 1767169003334,
-      "tag": "0004_add_chapter_content_and_kp_chapter",
-      "breakpoints": true
-    },
-    {
-      "idx": 5,
-      "version": "5",
-      "when": 1767751916045,
-      "tag": "0005_add_class_school_subject_teachers",
-      "breakpoints": true
-    },
-    {
-      "idx": 6,
-      "version": "5",
-      "when": 1767760693171,
-      "tag": "0006_faithful_king_bedlam",
-      "breakpoints": true
-    },
-    {
-      "idx": 7,
-      "version": "5",
-      "when": 1768205524480,
-      "tag": "0007_talented_bromley",
-      "breakpoints": true
-    },
-    {
-      "idx": 8,
-      "version": "5",
-      "when": 1768470966367,
-      "tag": "0008_thin_madrox",
-      "breakpoints": true
-    },
-    {
-      "idx": 9,
-      "version": "5",
-      "when": 1772162908476,
-      "tag": "0009_smart_mephistopheles",
-      "breakpoints": true
-    },
-    {
-      "idx": 10,
-      "version": "5",
-      "when": 1772439600000,
-      "tag": "0010_subject_id_switch",
+      "when": 1781676504560,
+      "tag": "0000_perfect_pestilence",
       "breakpoints": true
     }
   ]
-}
+}