Add Economics, Governance, and Mining SDKs for:
- Java: Full SDK with CompletableFuture async operations
- Kotlin: Coroutine-based SDK with suspend functions
- Swift: Modern Swift SDK with async/await
- Flutter/Dart: Complete Dart SDK with Future-based API
- C: Header files and implementations with opaque handles
- C++: Modern C++17 with std::future and PIMPL pattern
- C#: Records, async/await Tasks, and IDisposable
- Ruby: Struct-based types with Faraday HTTP client
Also includes minor Dart lint fixes (const exceptions).
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