feat: add server lifecycle management and D1 logging

- Add start/stop/reboot endpoints for server power management
- Add D1-based logging system (logs table + db-logger utility)
- Add idempotency_key validation for order deduplication
- Extend VPS provider interface with lifecycle methods

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/utils/db-logger.ts

@@ -0,0 +1,105 @@
+/**
+ * D1 기반 실시간 로깅 유틸리티
+ * console.log 대신 D1에 저장하여 나중에 조회 가능
+ */
+
+type LogLevel = 'info' | 'warn' | 'error';
+
+export interface DbLogger {
+  info: (message: string, context?: Record<string, unknown>) => void;
+  warn: (message: string, context?: Record<string, unknown>) => void;
+  error: (message: string, context?: Record<string, unknown>) => void;
+}
+
+/**
+ * D1에 로그 저장 (fire-and-forget, non-blocking)
+ */
+async function writeLog(
+  db: D1Database,
+  level: LogLevel,
+  service: string,
+  message: string,
+  context?: Record<string, unknown>
+): Promise<void> {
+  try {
+    await db.prepare(
+      'INSERT INTO logs (level, service, message, context) VALUES (?, ?, ?, ?)'
+    ).bind(
+      level,
+      service,
+      message,
+      context ? JSON.stringify(context) : null
+    ).run();
+  } catch (e) {
+    // DB 저장 실패 시 console로 fallback
+    console.error('[db-logger] Failed to write log:', e, { level, service, message, context });
+  }
+}
+
+/**
+ * 서비스별 로거 생성
+ */
+export function createDbLogger(db: D1Database, service: string): DbLogger {
+  return {
+    info: (message: string, context?: Record<string, unknown>) => {
+      console.log(`[${service}] ${message}`, context || '');
+      writeLog(db, 'info', service, message, context);
+    },
+    warn: (message: string, context?: Record<string, unknown>) => {
+      console.warn(`[${service}] ${message}`, context || '');
+      writeLog(db, 'warn', service, message, context);
+    },
+    error: (message: string, context?: Record<string, unknown>) => {
+      console.error(`[${service}] ${message}`, context || '');
+      writeLog(db, 'error', service, message, context);
+    },
+  };
+}
+
+/**
+ * 최근 로그 조회
+ */
+export async function getRecentLogs(
+  db: D1Database,
+  options?: {
+    level?: LogLevel;
+    service?: string;
+    limit?: number;
+  }
+): Promise<Array<{
+  id: number;
+  level: string;
+  service: string;
+  message: string;
+  context: string | null;
+  created_at: string;
+}>> {
+  const { level, service, limit = 100 } = options || {};
+
+  let query = 'SELECT * FROM logs WHERE 1=1';
+  const params: string[] = [];
+
+  if (level) {
+    query += ' AND level = ?';
+    params.push(level);
+  }
+  if (service) {
+    query += ' AND service = ?';
+    params.push(service);
+  }
+
+  query += ' ORDER BY created_at DESC LIMIT ?';
+  params.push(String(limit));
+
+  const stmt = db.prepare(query);
+  const result = await stmt.bind(...params).all();
+
+  return result.results as Array<{
+    id: number;
+    level: string;
+    service: string;
+    message: string;
+    context: string | null;
+    created_at: string;
+  }>;
+}

src/utils/index.ts

@@ -52,6 +52,13 @@ export {
   EXCHANGE_RATE_FALLBACK
 } from './exchange-rate';
 
+// D1 logging utilities
+export {
+  createDbLogger,
+  getRecentLogs
+} from './db-logger';
+export type { DbLogger } from './db-logger';
+
 // Re-export region utilities from region-utils.ts for backward compatibility
 export {
   DEFAULT_ANVIL_REGION_FILTER_SQL,