feat(settings): 用户级全局默认配置（per-user 落库 + 新建项目套默认）

新增 settings 表（user_id PK，data JSON，单本地用户 'local'）+ store.getSettings/putSettings
（内置默认=核心策略子集）+ GET/PUT /api/settings 端点；POST /api/projects 创建时以用户
默认填充未显式传的字段（body 优先，自动放行/预算经 patchProject 套用）。前端弹框另提交。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/store/index.ts

@@ -1,5 +1,5 @@
 export { Store, StoreError } from './store.js';
-export type { CreateProjectInput, CreateTaskInput, PatchProjectInput, PatchTaskInput, ActiveRun } from './store.js';
+export type { CreateProjectInput, CreateTaskInput, PatchProjectInput, PatchTaskInput, ActiveRun, UserSettings } from './store.js';
 export type { Metrics, DurationStats, RunStats, ReviewStats, RetryStats, ModelUsage } from '../model/metrics.js';
 export { openDb } from './db.js';
 export type { DB } from './db.js';