Add rules/perl/ with 5 rule files (coding-style, testing, patterns,
hooks, security) following the same structure as existing languages.
Update README.md, README.zh-CN.md, and rules/README.md to document
Perl support including badges, directory trees, install instructions,
and rule counts.
Add 5 rule files for Swift following the established pattern used by
TypeScript, Python, and Go rule sets. Covers Swift 6 strict concurrency,
Swift Testing framework, protocol-oriented patterns, Keychain-based
secret management, and SwiftFormat/SwiftLint hooks.