feat: add testing documentation and improve test configuration

[thisisnkc]

• Add comprehensive testing guide with setup instructions and examples
• Create centralized database configuration helper for test environments
• Add .env.testing.example template for test environment variables
• Update database driver tests to use configurable connections
• Fix test descriptions and improve DynamoDB endpoint configuration
• Update gitignore to exclude all .env files except examples

[changeset-bot[bot]]

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Latest commit: a7217596df8966652140b72aff100abc8fa096ef

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[Julien-R44]

Could you remove the testing.md file please? Because I think it doesn't make sense to include it in the public documentation

[thisisnkc]

okay got it, just pushed the changes