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/AGENTS.md

@@ -8,7 +8,7 @@ TanStack Start fullstack web app with ORPC (contract-first RPC) and shadcn/ui.
 
 - **Framework**: TanStack Start (React 19 SSR, file-based routing)
 - **Styling**: Tailwind CSS v4 + shadcn/ui (base-nova style, `@base-ui/react`)
-- **Database**: PostgreSQL + Drizzle ORM v1 beta (`drizzle-orm/postgres-js`, RQBv2)
+- **Database**: PostgreSQL + Drizzle ORM 0.45.x (`drizzle-orm/postgres-js`)
 - **State**: TanStack Query v5 (with MutationCache auto-invalidation)
 - **RPC**: ORPC (contract-first, type-safe)
 - **Auth**: Better Auth (email+password, single-owner, self-hosted)
@@ -99,7 +99,7 @@ src/
 ### 1. Define Contract (in module: `src/modules/feature/contract.ts`)
 ```typescript
 import { oc } from '@orpc/contract'
-import { createInsertSchema, createSelectSchema, createUpdateSchema } from 'drizzle-orm/zod'
+import { createInsertSchema, createSelectSchema, createUpdateSchema } from 'drizzle-zod'
 import { z } from 'zod'
 import * as schema from '@/modules/feature/schema'
 import { generatedFieldKeys } from '@/server/db/fields'
@@ -128,8 +128,8 @@ export const myResource = {
     .use(dbMiddleware).use(authMiddleware)
     .handler(async ({ context }) => {
       return await context.db.query.myTable.findMany({
-        where: { userId: context.user.id },
-        orderBy: { createdAt: 'desc' },
+        where: (t, { eq }) => eq(t.userId, context.user.id),
+        orderBy: (t, { desc }) => desc(t.createdAt),
       })
     }),
 
@@ -244,14 +244,16 @@ toast.success('操作成功')
 toast.error('操作失败')
 ```
 
-## Database (Drizzle ORM v1 beta)
+## Database (Drizzle ORM 0.45.x)
 
 - **Driver**: `drizzle-orm/postgres-js` (NOT `bun-sql`)
-- **Validation**: `drizzle-orm/zod` (built-in, NOT separate `drizzle-zod` package)
-- **Relations**: `defineRelations()` in `src/server/db/relations.ts` — RQBv2 object syntax
+- **Validation**: `drizzle-zod` (separate package, NOT `drizzle-orm/zod`)
+- **Relations**: `relations()` from `drizzle-orm` in `src/server/db/relations.ts` — callback syntax
 - **Table naming**: No `Table` suffix — `user`, `category`, `bookmark`
-- **DB instance**: Module-level singleton `export const db = drizzle(...)` (NOT factory pattern)
+- **DB instance**: Module-level singleton `export const db = drizzle(client, { schema })` (NOT factory pattern)
 - **Shared fields**: Use `...generatedFields` spread for id/createdAt/updatedAt
+- **Auth schema**: Generated by Better Auth CLI (`bun run db:auth`), **never hand-edit**
+- **Schema re-export**: `db/schema/index.ts` selectively exports tables only (not relations) from auth schema
 - **Migration workflow**: Always `db:generate` → `db:migrate`. **Never** use `db:push`.
 - **Path alias exception**: Files in the Drizzle schema chain (`db/schema/index.ts`, module `schema.ts`) MUST use relative imports — `drizzle-kit` does not resolve `@/*` aliases.
 
@@ -263,11 +265,12 @@ export const myTable = pgTable('my_table', {
   userId: text('user_id').notNull().references(() => user.id, { onDelete: 'cascade' }),
 })
 
-// Relations — RQBv2 defineRelations
-export const relations = defineRelations(schema, (r) => ({
-  myTable: {
-    user: r.one.user({ from: r.myTable.userId, to: r.user.id }),
-  },
+// Relations — callback syntax
+export const myTableRelations = relations(myTable, ({ one }) => ({
+  user: one(user, {
+    fields: [myTable.userId],
+    references: [user.id],
+  }),
 }))
 ```
 
@@ -293,8 +296,8 @@ Kairos is a self-hosted single-user app. There is NO public registration. The fi
 - Use `@/*` path aliases (not relative imports)
 - Use `render` prop (NOT `asChild`) for base-ui component delegation
 - Use `ORPCError` with proper codes
-- Use `drizzle-orm/zod` (NOT `drizzle-zod`)
-- Use RQBv2 object syntax for `orderBy` and `where`
+- Use `drizzle-zod` for schema validation (NOT `drizzle-orm/zod`)
+- Use callback syntax for `orderBy` and `where` in relational queries
 - Use `move()` from `@dnd-kit/helpers` for DnD reordering
 - Use `useState` callback ref for virtualizer scroll elements inside Dialogs
 
@@ -302,9 +305,9 @@ Kairos is a self-hosted single-user app. There is NO public registration. The fi
 - Add new `src/components/ui/*.tsx` without CLI (use `bunx shadcn@latest add` to scaffold, then freely customize)
 - Edit `src/routeTree.gen.ts` (auto-generated)
 - Use `asChild` prop (base-ui uses `render`, NOT Radix)
-- Import from `drizzle-zod` (use `drizzle-orm/zod`)
+- Import from `drizzle-orm/zod` (use `drizzle-zod`)
 - Use `drizzle-orm/bun-sql` driver
-- Pass `schema` to `drizzle()` constructor (only `relations` needed in RQBv2)
+- Hand-edit `src/server/auth/schema.ts` (generated by Better Auth CLI, use `bun run db:auth`)
 - Add `Table` suffix to Drizzle table exports
 - Use `useRef` for scroll elements inside Dialog/conditional rendering
 - Use `db:push` — always use `db:generate` → `db:migrate`