🧪 Add missing tests for AST components Program and Block

[Tcode-Motion]

🎯 What: This PR addresses the testing gap for AST nodes, specifically focusing on Program and Block components.\n\n📊 Coverage: The new tests cover the construction and serialization of Program and Block structs in compiler/ast/tests/ast_tests.rs. They verify properties, construction logic, and equality behavior as outlined in the issue rationale.\n\n✨ Result: Test coverage for the AST crate is improved, specifically providing safety for refactoring logic around these structures.

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PR created automatically by Jules for task 7892946119788546522 started by @Tcode-Motion

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