refactor: 降级 Drizzle ORM 至 0.45.x 稳定版，对齐 Better Auth 兼容性

- drizzle-orm 1.0.0-beta.15 → 0.45.2, drizzle-kit → 0.31.10
- RQBv2 defineRelations() → 旧版 relations() 回调语法
- drizzle-orm/zod → drizzle-zod 独立包
- auth/schema.ts 改由 Better Auth CLI 生成（bun run db:auth）
- db/schema/index.ts 选择性导出表（不导出生成文件中的旧版 relations）
- 删除 db:push script，强制 db:generate → db:migrate 工作流
- 重建迁移基线（删除旧迁移目录，全新生成初始迁移）

apps/server/package.json

@@ -15,9 +15,9 @@
     "compile:linux:x64": "bun compile.ts --target bun-linux-x64",
     "compile:windows": "bun run compile:windows:x64",
     "compile:windows:x64": "bun compile.ts --target bun-windows-x64",
+    "db:auth": "bunx auth@latest generate --output src/server/auth/schema.ts --yes",
     "db:generate": "drizzle-kit generate",
     "db:migrate": "drizzle-kit migrate",
-    "db:push": "drizzle-kit push",
     "db:studio": "drizzle-kit studio",
     "dev": "bunx --bun vite dev",
     "fix": "biome check --write",
@@ -46,6 +46,7 @@
     "class-variance-authority": "catalog:",
     "clsx": "catalog:",
     "drizzle-orm": "catalog:",
+    "drizzle-zod": "catalog:",
     "lucide-react": "catalog:",
     "next-themes": "catalog:",
     "postgres": "catalog:",