feat(roles): sort user list by role rank and username

优化 GET /api/roles/users 用户列表的排序：
- 主排序：按角色等级 皇帝 → 公爵 → 骑士 → 平民（无角色用户排最后）
- 次排序：用户名长度（短者优先）
- 末排序：用户名字母序（大小写不敏感）
- 查询由 db.query.users.findMany（relational）改为显式 select + leftJoin，
  以支持基于角色名的 CASE 排序

Sort the user list returned by GET /api/roles/users:
- Primary: by role rank Emperor -> Duke -> Knight -> Civilian (users
  without a role sort last)
- Secondary: username length (shorter first)
- Tertiary: username alphabetical order (case-insensitive)
- Switch the query from db.query.users.findMany (relational) to an explicit
  select + leftJoin to enable CASE-based ordering on role name

app/api/roles/users/route.ts

@@ -1,8 +1,8 @@
 import { createDb } from "@/lib/db"
-import { users } from "@/lib/schema"
+import { users, userRoles, roles } from "@/lib/schema"
 import { eq, like, or, sql } from "drizzle-orm"
 import { checkPermission } from "@/lib/auth"
-import { PERMISSIONS } from "@/lib/permissions"
+import { PERMISSIONS, ROLES } from "@/lib/permissions"
 
 export const runtime = "edge"
 
@@ -34,19 +34,30 @@ export async function GET(request: Request) {
       .where(searchCondition)
     const total = Number(totalResult[0].count)
 
-    const userList = await db.query.users.findMany({
-      where: searchCondition,
-      with: {
-        userRoles: {
-          with: {
-            role: true,
-          },
-        },
-      },
-      limit: pageSize,
-      offset: (page - 1) * pageSize,
-      orderBy: (users, { desc }) => [desc(users.id)],
-    })
+    const roleRank = sql`CASE COALESCE(${roles.name}, ${ROLES.CIVILIAN})
+      WHEN ${ROLES.EMPEROR} THEN 0
+      WHEN ${ROLES.DUKE} THEN 1
+      WHEN ${ROLES.KNIGHT} THEN 2
+      WHEN ${ROLES.CIVILIAN} THEN 3
+      ELSE 4
+    END`
+
+    const userList = await db
+      .select({
+        id: users.id,
+        name: users.name,
+        username: users.username,
+        email: users.email,
+        image: users.image,
+        role: roles.name,
+      })
+      .from(users)
+      .leftJoin(userRoles, eq(userRoles.userId, users.id))
+      .leftJoin(roles, eq(roles.id, userRoles.roleId))
+      .where(searchCondition)
+      .orderBy(roleRank, sql`LENGTH(COALESCE(${users.username}, ${users.name}))`, sql`LOWER(COALESCE(${users.username}, ${users.name}))`)
+      .limit(pageSize)
+      .offset((page - 1) * pageSize)
 
     return Response.json({
       users: userList.map((u) => ({
@@ -55,7 +66,7 @@ export async function GET(request: Request) {
         username: u.username,
         email: u.email,
         image: u.image,
-        role: u.userRoles[0]?.role.name || null,
+        role: u.role || null,
       })),
       total,
       page,