fix(source): change href type to str and add URL validation

[whitdog47]

This PR refactors the Link model to address issues related to JSON serialization. The primary changes involve replacing the AnyHttpUrl type with str in the SQLAlchemy model and implementing a robust validation mechanism at the API layer to ensure URLs are valid before being persisted to the database.

Key Changes

1. Model Update:

   • Changed the href field type from AnyHttpUrl to str in the Link SQLAlchemy model.
   • This change was necessary because AnyHttpUrl cannot be directly serialized to JSON, and the list of Link objects are stored as JSON in the source table.

2. Validation Mechanism:

   • We introduced a validation function using Pydantic's AnyHttpUrl to validate URLs before they are stored in the database.
   • This ensures that only valid URLs are persisted, while maintaining the flexibility to store them as strings.

[Copilot]

Pull Request Overview

This PR refactors URL handling for the Link model by switching the href type from AnyHttpUrl to str and adding an API layer validation mechanism using Pydantic.

• Update of the Link model in models.py to use str for href with a comment noting the change for JSON serialization.
• Introduction of a LinkValidator and an all_links_are_valid function in service.py for URL validation before database persistence.
• Minor adjustments in error handling in get_by_name_or_raise for missing sources.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/dispatch/data/source/service.py	Added URL validation logic, logging for invalid URLs, and updated error handling in source retrieval.
src/dispatch/data/source/models.py	Changed the Link.href type from AnyHttpUrl to str and updated inline documentation about URL validation.