RustCloud: Multi-Cloud GenAI Provider Integrations & BigQuery Support

RustCloud unifies cloud provider APIs for Rust developers, but Generative AI support is completely missing. Every GenAI provider uses a different auth model, API style, and request format, forcing developers to maintain separate HTTP clients for each one. Rust has no equivalent of Python's LiteLLM or LangChain. This project delivers concrete LlmProvider implementations for AWS Bedrock, GCP Vertex AI, and Azure OpenAI, a complete GCP BigQuery module, a UnifiedLlmClient with Explicit/ModelBased/Fallback routing strategies, RetryMiddleware with exponential backoff, and a full test suite targeting 85%+ coverage with complete documentation. I have been contributing to RustCloud since March 2026 with 19 PRs across all four cloud providers, including working proof-of-concept implementations of all three GenAI providers and the routing layer. The GSoC period is where these drafts become production-quality, tested, and merged modules.