🛠 Centralize region configuration

[AlexanderWiechert]

🛠 Centralize region configuration

The region is currently hardcoded in several places as "EU (Frankfurt)". We want to support centralized region configuration.

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📦 Implementation Plan

• Create core/config.py with DEFAULT_REGION = "eu-central-1"
• Add CLI flag --region to override it
• Refactor pricing and filter logic to use this setting

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🧪 Tests

• Validate region override via CLI
• Ensure fallbacks work with no region specified

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🧱 Notes

Supports multi-region analysis and prepares the project for broader coverage.