Export RenderConversationConfig from crate root

[JayYarlagadda]

Summary

• re-export RenderConversationConfig from the crate root
• show how Rust callers can customize auto_drop_analysis
• document the rendering configuration in the Rust API guide

Tests

• cargo fmt --check
• cargo test --doc
• cargo test --all-targets --all-features (30 passed)
• pytest (42 passed)

Closes #73

[chatgpt-codex-connector]

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[sylvesterkaczmarek]

Checked the current head after the earlier docs correction. The crate-root re-export matches the documented import path, and the docs now correctly separate None from Some(&RenderConversationConfig::default()). I don't see a remaining compatibility issue in this change.