Implement custom Error derive macro

[RAprogramm]

Summary

• Introduced the masterror-derive proc-macro crate that generates Display and std::error::Error implementations with format rewrites and source handling.
• Replaced thiserror usage across the crate by re-exporting the new derive and updating module imports and documentation.
• Added integration tests that exercise the derive on structs and enums to verify formatting and source propagation.

Testing

• cargo +nightly fmt
• cargo clippy -- -D warnings
• cargo test
• cargo doc --no-deps

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https://chatgpt.com/codex/tasks/task_e_68ca25bc3e4c832b816e4310e46b588a