fix: 自定义规则置顶生效，写入前校验策略名存在

规则首条匹配即生效，自定义规则此前插在模板规则之后、FINAL 之前，被
download.conf 等宽泛规则集抢先命中（brew.sh 配了代理仍直连）。现在新建
规则插到 seq 0，重新播种时也把自定义规则整体排在模板规则之前。

同时把 BUILTIN_POLICIES 提到 shared 共用，规则新建／编辑时校验策略必须是
内置策略或已有策略组，避免引用不存在的策略被 IR 静默剔除；前端表单默认
策略由不存在的「Proxy」改为 DIRECT。

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/services/ir.ts

@@ -1,7 +1,7 @@
 import { asc, eq } from 'drizzle-orm';
 import { db } from '../db/index.js';
 import { groupMembers, nodes, policyGroups, rules, rulesets, settings } from '../db/schema.js';
-import type { NodeDto } from '@proxy-station/shared';
+import { BUILTIN_POLICIES, type NodeDto } from '@proxy-station/shared';
 import { rowToDto } from '../routes/nodes.js';
 
 export interface GroupIR {
@@ -71,9 +71,9 @@ export function buildProfileIR(opts: { nodeIds?: string[] } = {}): ProfileIR {
   // 停用的组从输出中剔除；引用它的成员与规则一并跳过，保证产物有效
   const groupRows = allGroupRows.filter((g) => g.enabled);
   const liveNames = new Set(groupRows.map((g) => g.name));
-  const BUILTIN_POLICIES = new Set(['DIRECT', 'REJECT', 'REJECT-DROP', 'REJECT-NO-DROP', 'REJECT-TINYGIF']);
+  const builtins = new Set<string>(BUILTIN_POLICIES);
   /** 组已被删除或停用时，引用它的成员/规则应当跳过 */
-  const isDeadRef = (name: string) => !liveNames.has(name) && !BUILTIN_POLICIES.has(name);
+  const isDeadRef = (name: string) => !liveNames.has(name) && !builtins.has(name);
   const groups: GroupIR[] = groupRows.map((g) => ({
     name: g.name,
     type: g.type,