[2d] Delete legacy arfset.api.js and asm.js build targets (major version breaking change)

[kalwalt]

Summary

Delete legacy js/arfset.api.js global-API file and drop asm.js build targets (major-version breaking change)

Environment

• Product/Service: FeatureSET-Display — JavaScript API & build system
• Files: js/arfset.api.js, js/jslibrary.js, tools/makem.js, example/example.html, build/arfset.min.js, build/arfset.debug.js

Problem Description

js/arfset.api.js is a legacy global-ARfset API tightly coupled to the asm.js outputs. It is injected via --pre-js into arfset.debug.js and arfset.min.js only (tools/makem.js:176). The wasm and ES6-wasm builds never include it. Modern browsers have full wasm support, making both the legacy API and the asm.js targets unnecessary. Only example/example.html currently consumes it; a working example_es6.html already exists as a drop-in replacement.

Expected Behavior

• js/arfset.api.js is deleted.
• js/jslibrary.js is deleted (once issue 1b removes writeFP/writeFS).
• compile_combine and compile_combine_min jobs removed from tools/makem.js, along with PRE_FLAGS.
• example/example.html migrated to the ES6 build (or replaced by example_es6.html).
• build/arfset.min.js and build/arfset.debug.js deleted; no longer generated.
• Legacy window.ARFset global still accessible via the existing webpack UMD bundle (dist/ARFset.js).
• README documents the removal; version bumped to a new major version.

Actual Behavior

Legacy asm.js build targets and the arfset.api.js file are still generated and maintained, adding build complexity and a maintenance surface for outdated code.

Tasks

• Delete js/arfset.api.js
• Delete js/jslibrary.js once issue 1b lands (removes writeFP/writeFS; --js-library flag goes away)
• Remove compile_combine and compile_combine_min jobs from tools/makem.js, plus the PRE_FLAGS block
• Migrate example/example.html to the ES6 build (or replace with example_es6.html)
• Delete build/arfset.min.js and build/arfset.debug.js; stop generating them
• Verify window.ARFset global is still exposed via the webpack UMD bundle (dist/ARFset.js)
• Note the removal in the README and bump to a new major version

Impact

High — Breaking change for anyone loading arfset.min.js or arfset.debug.js directly. Requires a major version bump. Simplifies the build significantly and removes dead code.

Additional Context

Dependencies: Issue 1b must land first to safely delete js/jslibrary.js. This issue can be split: delete arfset.api.js + drop asm.js targets first, then delete jslibrary.js in a follow-up after 1b.

The webpack UMD bundle (dist/ARFset.js) already exposes window.ARFset, so no separate legacy entry point is needed to maintain backward compatibility for UMD consumers.