feat: Rust Idioms

[duyet]

• Expand format.md with detailed examples and best practices
• Expand constructor.md with multiple patterns and real-world examples
• Add finalisation-destructors.md covering Drop trait and RAII
• Add mem-replace.md explaining mem::take and mem::replace patterns
• Add privacy-for-extensibility.md for API design best practices
• Add option-iter.md showing Option iteration patterns
• Add pass-variables-to-closure.md covering closure capture modes
• Add let-else.md documenting modern Rust pattern matching

All new idioms include:

• Comprehensive explanations in Vietnamese
• Practical code examples
• Best practices and anti-patterns
• Real-world use cases
• Performance considerations

🤖 Generated with Claude Code

[github-actions]

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