Build a Weather Dashboard Backend

Problem/Feature Description

Build a Python Flask API that aggregates weather data from the OpenWeatherMap API and caches results in Redis. The frontend team will consume this API.

Endpoints:

• GET /api/weather/:city -- get current weather for a city (cached for 10 minutes)
• GET /api/weather/:city/forecast -- get 5-day forecast (cached for 30 minutes)
• GET /api/weather/favorites -- get weather for all favorited cities
• POST /api/weather/favorites -- add a city to favorites (stored in SQLite)
• DELETE /api/weather/favorites/:city -- remove a city from favorites

Business rules:

• City names are case-insensitive and trimmed of whitespace
• If Redis is unavailable, the API should still work (skip cache, fetch directly)
• Maximum 20 favorite cities per user (use a simple API key for user identification)
• Rate limit external API calls to avoid hitting OpenWeatherMap limits

Use requests for HTTP calls, redis for caching, and sqlite3 for favorites storage.

Output Specification

Produce:

• app/__init__.py -- Flask application factory
• app/routes/weather.py -- weather route handlers
• app/routes/favorites.py -- favorites route handlers
• app/weather_client.py -- OpenWeatherMap API integration
• app/cache.py -- Redis cache layer
• app/db.py -- SQLite database setup
• requirements.txt -- with dependencies
• .gitignore -- standard Python gitignore

You may create additional files as needed for a well-structured codebase.