feat: added telegram daemon and systemd service configuration

backend/scripts/radionica-telegram.service

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+[Unit]
+Description=Radionica3D Telegram Queue Daemon
+After=network.target redis.service
+
+[Service]
+Type=simple
+User=www-data
+Group=www-data
+WorkingDirectory=/var/www/radionica3d/backend
+Environment=PYTHONPATH=/var/www/radionica3d/backend
+Environment=REDIS_HOST=localhost
+Environment=REDIS_PORT=6379
+# BOT_TOKEN should be set here or in a separate env file
+Environment=BOT_TOKEN=YOUR_BOT_TOKEN_HERE
+ExecStart=/var/www/radionica3d/backend/venv/bin/python scripts/telegram_daemon.py
+Restart=always
+RestartSec=10
+
+[Install]
+WantedBy=multi-user.target

backend/scripts/telegram_daemon.py

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+import os
+import time
+import json
+import redis
+import requests
+import logging
+
+# Configure logging
+logging.basicConfig(
+    level=logging.INFO,
+    format='%(asctime)s [%(levelname)s] %(message)s',
+    handlers=[logging.StreamHandler()]
+)
+
+# Configuration from Environment
+BOT_TOKEN = os.getenv("BOT_TOKEN")
+REDIS_HOST = os.getenv("REDIS_HOST", "localhost")
+REDIS_PORT = int(os.getenv("REDIS_PORT", 6379))
+QUEUE_NAME = "messages_queue"
+
+def send_telegram_message(chat_id, text):
+    if not BOT_TOKEN:
+        logging.error("BOT_TOKEN not found in environment variables")
+        return False
+    
+    url = f"https://api.telegram.org/bot{BOT_TOKEN}/sendMessage"
+    payload = {
+        "chat_id": chat_id,
+        "text": text,
+        "parse_mode": "HTML"
+    }
+    
+    try:
+        response = requests.post(url, json=payload, timeout=10)
+        response.raise_for_status()
+        logging.info(f"Successfully sent message to {chat_id}")
+        return True
+    except Exception as e:
+        logging.error(f"Failed to send message to {chat_id}: {e}")
+        return False
+
+def main():
+    logging.info("Telegram Daemon starting...")
+    
+    if not BOT_TOKEN:
+        logging.error("BOT_TOKEN is not set! Daemon will exit.")
+        return
+
+    try:
+        r = redis.Redis(host=REDIS_HOST, port=REDIS_PORT, decode_responses=True)
+        # Test connection
+        r.ping()
+        logging.info(f"Connected to Redis at {REDIS_HOST}:{REDIS_PORT}")
+    except Exception as e:
+        logging.error(f"Could not connect to Redis: {e}")
+        return
+
+    while True:
+        try:
+            # BLPOP blocks until a message is available
+            # It returns a tuple (queue_name, value)
+            item = r.blpop(QUEUE_NAME, timeout=10)
+            
+            if item:
+                _, value = item
+                try:
+                    data = json.loads(value)
+                    chat_id = data.get("id")
+                    message = data.get("message")
+                    
+                    if chat_id and message:
+                        send_telegram_message(chat_id, message)
+                        
+                        # Anti-spam/Rate-limit logic
+                        queue_len = r.llen(QUEUE_NAME)
+                        if queue_len > 2:
+                            logging.info(f"Queue size is {queue_len} (> 2). Sleeping for 30s...")
+                            time.sleep(30)
+                        else:
+                            # Small pause to avoid CPU hogging
+                            time.sleep(0.5)
+                    else:
+                        logging.warning(f"Invalid message format: {value}")
+                        
+                except json.JSONDecodeError:
+                    logging.error(f"Failed to decode message JSON: {value}")
+            
+        except Exception as e:
+            logging.error(f"Error in daemon loop: {e}")
+            time.sleep(5) # Wait before retry
+
+if __name__ == "__main__":
+    main()