refactor: 全面优化后端代码质量与架构

- app.ts 单体路由拆分为 routes/ + helpers + middleware + static 独立模块
- 类型去重：CheckFailure/CheckResult 以 shared/api.ts 为唯一源头，收紧 phase 联合类型
- es-toolkit 替换：isPlainObject/isNil/isEmptyObject/isEqual/isError/Semaphore/groupBy
- Bun 内置 API：Object.fromEntries 替代手写 headersToRecord
- bun:sqlite 规范：prepare() → query() 利用内置缓存，避免 N+1 查询
- 新增 getLatestChecksMap/allGetTargetStats 批量查询方法
- 新增 backend-code-quality/api-route-separation/batch-data-queries 规范
- 补充 openspec/config.yaml 后端开发规范与 DEVELOPMENT.md 后端开发指引

src/server/checker/store.ts

@@ -112,7 +112,7 @@ export class ProbeStore {
   }): void {
     if (this.closed) return;
     this.db
-      .prepare(
+      .query(
         "INSERT INTO check_results (target_id, timestamp, matched, duration_ms, status_detail, failure) VALUES (?, ?, ?, ?, ?, ?)",
       )
       .run(
@@ -139,12 +139,12 @@ export class ProbeStore {
     pageSize = 20,
   ): { items: StoredCheckResult[]; total: number; page: number; pageSize: number } {
     const countRow = this.db
-      .prepare("SELECT COUNT(*) as total FROM check_results WHERE target_id = ? AND timestamp >= ? AND timestamp <= ?")
+      .query("SELECT COUNT(*) as total FROM check_results WHERE target_id = ? AND timestamp >= ? AND timestamp <= ?")
       .get(targetId, from, to) as { total: number };
 
     const offset = (page - 1) * pageSize;
     const items = this.db
-      .prepare(
+      .query(
         "SELECT * FROM check_results WHERE target_id = ? AND timestamp >= ? AND timestamp <= ? ORDER BY timestamp DESC LIMIT ? OFFSET ?",
       )
       .all(targetId, from, to, pageSize, offset) as StoredCheckResult[];
@@ -157,7 +157,7 @@ export class ProbeStore {
     availability: number;
   } {
     const row = this.db
-      .prepare(
+      .query(
         `SELECT
           COUNT(*) as totalChecks,
           COALESCE(SUM(CASE WHEN matched = 1 THEN 1 ELSE 0 END), 0) as upCount
@@ -186,7 +186,7 @@ export class ProbeStore {
     totalChecks: number;
   }> {
     return this.db
-      .prepare(
+      .query(
         `SELECT
           strftime('%Y-%m-%dT%H:00:00', timestamp) as hour,
           AVG(CASE WHEN matched = 1 THEN duration_ms END) as avgDurationMs,
@@ -212,12 +212,13 @@ export class ProbeStore {
     lastCheckTime: string | null;
   } {
     const targets = this.getTargets();
+    const latestChecksMap = this.getLatestChecksMap();
     let up = 0;
     let down = 0;
     let lastCheckTime: string | null = null;
 
     for (const target of targets) {
-      const latest = this.getLatestCheck(target.id);
+      const latest = latestChecksMap.get(target.id);
 
       if (latest) {
         if (latest.matched) {
@@ -247,7 +248,7 @@ export class ProbeStore {
     limit: number,
   ): Array<{ timestamp: string; duration_ms: number | null; matched: number }> {
     return this.db
-      .prepare(
+      .query(
         "SELECT timestamp, duration_ms, matched FROM check_results WHERE target_id = ? ORDER BY timestamp DESC LIMIT ?",
       )
       .all(targetId, limit) as Array<{
@@ -257,6 +258,38 @@ export class ProbeStore {
     }>;
   }
 
+  getLatestChecksMap(): Map<number, StoredCheckResult> {
+    const rows = this.db
+      .query(
+        `SELECT cr.* FROM check_results cr
+         INNER JOIN (
+           SELECT target_id, MAX(timestamp) as max_ts
+           FROM check_results
+           GROUP BY target_id
+         ) latest ON cr.target_id = latest.target_id AND cr.timestamp = latest.max_ts`,
+      )
+      .all() as StoredCheckResult[];
+    return new Map(rows.map((r) => [r.target_id, r]));
+  }
+
+  getAllTargetStats(): Map<number, { totalChecks: number; availability: number }> {
+    const rows = this.db
+      .query(
+        `SELECT target_id, COUNT(*) as totalChecks,
+          COALESCE(SUM(CASE WHEN matched = 1 THEN 1 ELSE 0 END), 0) as upCount
+         FROM check_results
+         GROUP BY target_id`,
+      )
+      .all() as Array<{ target_id: number; totalChecks: number; upCount: number }>;
+
+    const result = new Map<number, { totalChecks: number; availability: number }>();
+    for (const row of rows) {
+      const availability = row.totalChecks > 0 ? Math.round((row.upCount / row.totalChecks) * 10000) / 100 : 0;
+      result.set(row.target_id, { totalChecks: row.totalChecks, availability });
+    }
+    return result;
+  }
+
   close(): void {
     this.closed = true;
     this.db.close();