feat: initial flight monitor

- Python flight price monitor for BER↔EZE and other routes
- Adapter pattern for extensibility (Kiwi/Tequila implemented)
- OpenClaw alerting integration
- Cron-friendly one-shot execution
- Full logging of all checks
- Graceful handling when API key not set

Implements monkey-island/flight-monitor#2

adapters/kiwi.py

@@ -0,0 +1,120 @@
+"""
+Kiwi.com / Tequila API adapter.
+"""
+import os
+import logging
+from datetime import date, datetime
+from typing import List, Dict, Any
+import requests
+
+from adapters.base import FlightAdapter
+
+
+logger = logging.getLogger(__name__)
+
+
+class KiwiAdapter(FlightAdapter):
+    """
+    Adapter for Kiwi.com Tequila API.
+    
+    API docs: https://tequila.kiwi.com/docs/search/
+    """
+    
+    API_BASE = "https://api.tequila.kiwi.com"
+    
+    def __init__(self):
+        """Initialize the adapter. Requires KIWI_API_KEY environment variable."""
+        self.api_key = os.getenv("KIWI_API_KEY")
+        if not self.api_key:
+            raise ValueError(
+                "KIWI_API_KEY environment variable not set. "
+                "Get your API key from https://tequila.kiwi.com/portal/login"
+            )
+        logger.info("Kiwi adapter initialized")
+    
+    def get_name(self) -> str:
+        return "Kiwi/Tequila"
+    
+    def search_round_trip(
+        self,
+        origin: str,
+        destination: str,
+        departure_date: date,
+        return_date: date,
+        **kwargs
+    ) -> List[Dict[str, Any]]:
+        """
+        Search for round-trip flights via Kiwi API.
+        
+        Args:
+            origin: IATA code (e.g., "BER")
+            destination: IATA code (e.g., "EZE")
+            departure_date: Departure date
+            return_date: Return date
+        
+        Returns:
+            List of normalized flight results.
+        """
+        url = f"{self.API_BASE}/v2/search"
+        
+        params = {
+            "fly_from": origin,
+            "fly_to": destination,
+            "date_from": departure_date.strftime("%d/%m/%Y"),
+            "date_to": departure_date.strftime("%d/%m/%Y"),
+            "return_from": return_date.strftime("%d/%m/%Y"),
+            "return_to": return_date.strftime("%d/%m/%Y"),
+            "flight_type": "round",
+            "adults": 1,
+            "curr": "EUR",
+            "limit": 5,
+            "sort": "price"
+        }
+        
+        headers = {
+            "apikey": self.api_key,
+            "accept": "application/json"
+        }
+        
+        try:
+            logger.debug(f"Kiwi API request: {origin}→{destination} {departure_date} → {return_date}")
+            response = requests.get(url, params=params, headers=headers, timeout=30)
+            response.raise_for_status()
+            
+            data = response.json()
+            results = []
+            
+            for item in data.get("data", []):
+                # Extract airline(s) - may be multiple for multi-leg flights
+                airlines = set()
+                for route in item.get("route", []):
+                    airline = route.get("airline")
+                    if airline:
+                        airlines.add(airline)
+                airline_str = ", ".join(sorted(airlines)) if airlines else "Unknown"
+                
+                # Parse timestamps
+                departure_time = datetime.fromtimestamp(item.get("dTime", 0))
+                return_time = datetime.fromtimestamp(item.get("aTime", 0))
+                
+                # Build deep link
+                deep_link = item.get("deep_link", "")
+                
+                results.append({
+                    "price_eur": float(item.get("price", 0)),
+                    "airline": airline_str,
+                    "departure": departure_time,
+                    "return": return_time,
+                    "link": deep_link,
+                    "source": self.get_name()
+                })
+            
+            logger.debug(f"Kiwi API returned {len(results)} results")
+            return results
+            
+        except requests.exceptions.RequestException as e:
+            logger.error(f"Kiwi API request failed: {e}")
+            return []
+        except Exception as e:
+            logger.error(f"Error parsing Kiwi API response: {e}")
+            return []