Fix ItemListView to accept viewModel via init with default parameter
so previews can inject mocks. Fix ExpensiveChartView Equatable to
compare full array instead of only count.
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.