[2e] Replace hardcoded _setup(893, 1117) with ARFset constructor options

[kalwalt]

Summary

Replace hardcoded _setup(893, 1117) magic numbers with configurable ARFset constructor options

Environment

• Product/Service: FeatureSET-Display — JavaScript API
• File: src/ARFset.js:249-251

Problem Description

The ARFset constructor calls _setup(893, 1117) with hardcoded canvas dimensions. These magic numbers are undocumented, cannot be overridden by callers, and do not reflect real use-case canvas sizes. Any application needing a different canvas size must patch the source.

Expected Behavior

The ARFset constructor accepts an optional { width, height } options object with sensible defaults (e.g. { width: 893, height: 1117 } to maintain existing behavior). Callers can override dimensions without modifying the library.

Actual Behavior

Canvas dimensions are hardcoded in the constructor; no way for callers to specify a different size.

Tasks

• Accept { width, height } in the ARFset constructor with defaults matching current hardcoded values
• Pass the options through to _setup(width, height)
• Update example HTML files (example/example.html, example_es6.html) to explicitly pass dimensions or rely on defaults

Impact

Low — Usability improvement; no functional regression. Current defaults preserve existing behavior.

Additional Context

This is a non-breaking change if defaults match current hardcoded values (893 × 1117). Consider also accepting a single canvas element reference as an alternative constructor signature to read dimensions from the DOM element directly.