Add database integration with PostgreSQL and ActiveRecord

[GrimbiXcode]

Changes

This PR adds database integration to ProductMiner, enabling the storage of product prices and metadata.

New Features

• PostgreSQL Integration: Added pg and activerecord gems for database support
• Database Models: Product and Price models to store product information and price history
• Database Configuration: config/database.yml for environment-specific settings
• Migration: Initial schema for products and prices tables
• Enhanced Foreman: Now saves fetched prices to the database
• Improved Error Handling: Added retries with exponential backoff for API calls
• RSpec Tests: Added comprehensive tests for MigrosApi and Foreman

Files Changed

• Added: config/database.yml, lib/product_miner/db.rb, lib/product_miner/models/product.rb, lib/product_miner/models/price.rb, db/migrate/20260603000000_create_products_and_prices.rb, spec/spec_helper.rb, spec/miners/migros_api_spec.rb, spec/foreman/foreman_spec.rb
• Modified: Gemfile, lib/product_miner/foreman/foreman.rb, lib/product_miner/miners/migros_api.rb, lib/product_miner.rb, Rakefile, .gitignore

How to Use

1. Setup PostgreSQL:
   docker run --name pm-postgres -e POSTGRES_PASSWORD=your_password -p 5432:5432 -d postgres

2. Create databases:
   createdb product_miner
   createdb product_miner_test

3. Run migrations:
   rake db:setup

4. Install jobs:
   rake jobs:install

5. Run tests:
   rspec

Next Steps

• Add configuration file for multiple products
• Implement product management CLI
• Add more miners (e.g., Coop, Digitec)
• Create web interface (Rails)

Closes #1 (First Miner - reduced features)