//! LLM API client for HS code classification (implemented in v0.4).
//!
//! This module will provide:
//! - Async client for Claude / OpenAI-compatible APIs
//! - Context-aware prompt builder using product description + SMILES analysis
//! - Structured output parsing (HS code + confidence + rationale)
//!
//! Enabled by the **`llm`** Cargo feature.
//! A mock client for testing is available via the **`mock`** feature.
// v0.4 TODO: implement LlmClient, LlmConfig, and mock client