🧹 Refactor _register_tools to fix long function code smell

[joy7758]

🎯 What: Extracted the monolithic _register_tools method into three smaller, logical groupings (_register_core_tools, _register_cloud_tools, _register_evaluation_tools). The original _register_tools method now delegates to these three new helpers.
💡 Why: _register_tools was 272 lines long, containing many nested definitions. Splitting it improves readability and maintainability without altering functionality.
✅ Verification: Ran ruff format and ruff check on the file to ensure stylistic correctness. Executed the full unit test suite, confirming no regressions. Verified the custom validate_governance.py and validate_milestone.py script checks.
✨ Result: The runtime_mcp_server.py codebase is cleaner and adheres to better software engineering practices regarding function length.

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PR created automatically by Jules for task 13167887666024849926 started by @joy7758

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