🧹 [Remove unused parser code allowance]

[Tcode-Motion]

🎯 What: Removed the #[allow(dead_code)] attribute from the Parser implementation, deleted the unused current_span and prev_span methods, and removed the unused Span import.
💡 Why: Suppressing warnings with #[allow(dead_code)] hides potential issues and clutters the codebase with unused functionality. Removing the dead code directly improves maintainability and readability.
✅ Verification: Ran cargo check -p techscript_parser, cargo fmt --all, and cargo test --workspace to verify that no functionality was broken and no new warnings were introduced.
✨ Result: A cleaner codebase with no unnecessary code allowances or unused code paths in the parser module.

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PR created automatically by Jules for task 17790725839574516037 started by @Tcode-Motion

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