feat: add contenthash table

[pikonha]

contenthash table

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Description

This pull request adds a new contenthash table to decouple content hash storage from the domains table. This change improves the database structure and allows for more flexible management of content hashes.

Key Changes:

1. Created a new Contenthash entity in packages/gateway/src/entities/index.ts.
2. Updated the PostgresRepository in packages/gateway/src/repositories/postgres.ts to handle the new Contenthash entity:
   • Added setContentHash method to upsert content hash data.
   • Modified getContentHash method to query the new Contenthash table.
   • Updated getSubdomains method to include content hash data.
3. Adjusted the content hash handlers in packages/gateway/src/handlers/contenthash.ts to work with the new table structure.

Related Issue

161

Changes

• [ ] New feature implementation
• [ ] Bug fix
• [X] Code refactoring
• [ ] Documentation update
• [ ] Other (please specify)

Changes to Core Features:

• [x] Have you added an explanation of what your changes do and why you'd like us to include them?
• [X] Have you written new tests for your core changes, as applicable?
• [X] Have you successfully run tests with your changes locally?