Implements `RenderedImage` with `ObjectFinalize` and `adjust_external_memory` to properly manage Rust-allocated pixel buffers in Node.js native addon memory accounting. This pattern is reusable for any napi-rs project that needs to avoid memory leaks when transferring large binary data to JavaScript.

Defines `FitToDef` enum and `CropOptions` struct with custom serde deserialization from JavaScript objects. The `FitToDef` enum elegantly models scaling modes (original, width, height, zoom) and its serialization/deserialization logic can be extracted for any Rust library that needs to accept polymorphic options from JS bindings.

Contains `render_inner_catch_unwind` which wraps Rust panics with `std::panic::catch_unwind` and converts them into JavaScript errors. This pattern is essential for any Rust-based Node.js addon using napi-rs where panics must not crash the Node.js process, and can be reused as a generic wrapper for fallible operations.

Implements separate font loading strategies for native (system fonts + custom files/directories) and WASM environments (preloaded buffer fonts including WOFF2). The pattern of conditionally compiling font sources and providing fallback logic is reusable for any cross-platform Rust library that needs to handle font availability differences.