✨ add text measurement helpers

[rauhryan]

Summary

• add pure TypeScript text measurement helpers exported from mod.ts
• port the renderer wcwidth table to TypeScript so helper widths match renderer layout for zero-width/default-ignorable codepoints
• document helper API and large-input behavior in specs/renderer-spec.md
• normalize oversized text packing failures to descriptive RangeError messages
• add coverage for wrap modes, Unicode widths, no-WASM/no-UTF8-staging measurement, default-ignorable width handling, and large UTF-8 projection rendering
• merge latest upstream main into the PR branch

Test

• scripts/run-checks 30 --include-uncommitted

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/clayterm@30

commit: c099165

[cowboyd]

I'm a bit worried that these measurement helpers present a completely different code path than the actual algorithm that clay uses to layout text. This could be a totally separate library.

[43081j]

this is pretty much what the npm package fast-string-width exists for, and fast-wrap-ansi (but smaller, and probably faster).

presumably clay itself also does yet another implementation of this under the hood like @cowboyd mentioned.

this does raise a side question too: can we not have npm dependencies? it doesn't make much sense to duplicate what's already in most peoples' stacks imo

[natemoo-re]

I'm curious to understand the motivation behind the pre-init behavior here, is that strictly necessary? Exposing a pure wrapper that calls into the wasm to check bytes against the existing wcwidth table would be feasible and avoid the code duplication concerns. We shouldn't need additional implementations of utils we already use internally.

In any case, I opened #72 to discuss this more generally. It's clear we'll need some kind of measurement helper.