Initial commit: Telegram bot with Cloudflare Workers

- OpenAI GPT-4o-mini with Function Calling
- Cloudflare D1 for user profiles and message buffer
- Sliding window (3 summaries max) for infinite context
- Tools: weather, search, time, calculator
- Workers AI fallback support
- Webhook security with rate limiting

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

schema.sql

@@ -0,0 +1,42 @@
+-- Telegram Bot Rolling Summary Schema
+-- D1 Database for Cloudflare Workers
+
+-- 사용자 테이블
+CREATE TABLE IF NOT EXISTS users (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  telegram_id TEXT UNIQUE NOT NULL,
+  username TEXT,
+  first_name TEXT,
+  created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+  updated_at DATETIME DEFAULT CURRENT_TIMESTAMP
+);
+
+-- 메시지 버퍼 (요약 전 임시 저장)
+CREATE TABLE IF NOT EXISTS message_buffer (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  user_id INTEGER NOT NULL,
+  chat_id TEXT NOT NULL,
+  role TEXT NOT NULL CHECK(role IN ('user', 'bot')),
+  message TEXT NOT NULL,
+  created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+  FOREIGN KEY (user_id) REFERENCES users(id)
+);
+
+-- 요약 저장 테이블 (슬라이딩 윈도우: 최대 3개만 유지)
+CREATE TABLE IF NOT EXISTS summaries (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  user_id INTEGER NOT NULL,
+  chat_id TEXT NOT NULL,
+  generation INTEGER NOT NULL DEFAULT 1,
+  summary TEXT NOT NULL,
+  message_count INTEGER NOT NULL,
+  created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+  FOREIGN KEY (user_id) REFERENCES users(id)
+);
+
+-- 인덱스
+CREATE INDEX IF NOT EXISTS idx_buffer_user ON message_buffer(user_id);
+CREATE INDEX IF NOT EXISTS idx_buffer_chat ON message_buffer(user_id, chat_id);
+CREATE INDEX IF NOT EXISTS idx_summary_user ON summaries(user_id, chat_id);
+CREATE INDEX IF NOT EXISTS idx_summary_latest ON summaries(user_id, chat_id, generation DESC);
+CREATE INDEX IF NOT EXISTS idx_users_telegram ON users(telegram_id);