🧪 [Add test for database module registration]

[Tcode-Motion]

🎯 What: Adds missing test for module registration in stdlib/src/database.rs.
📊 Coverage: The new test verifies the happy path of StdlibRegistry::register_database(&mut self). It ensures that std.database module is correctly registered, its exports contains connect, query, execute, and close, and its version is exactly "1.0.0".
✨ Result: Test coverage for std.database registration is now in place and confirmed passing by standard Cargo test suite.

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PR created automatically by Jules for task 6414082923065988856 started by @Tcode-Motion

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