fix: keep element text in simplifyHtmlElement

[DavertMik]

What was wrong

simplifyHtmlElement() calls removeNonInteractiveElements(), which strips non-interactive descendants. When an interactive element's visible label lives in nested <span>s (icon + badge + text button markup), everything inside is removed and the element serializes as an empty shell.

import { simplifyHtmlElement } from './lib/html.js'
const html = `<button type="button"><span class="content inline-flex items-center gap-3 w-full"><span class="badge badge-type manual"><svg class="md-icon md-icon-file-document-outline"></svg></span><span>New test</span></span></button>`
console.log(simplifyHtmlElement(html))

Before:

<button type="button"><span class="content inline-flex items-center w-full"></span></button>

After:

<button type="button"><span class="content inline-flex items-center w-full"><span>New test</span></span></button>

Why it matters

WebElement.toSimplifiedHTML() is the only caller, and it feeds MultipleElementsFound, whose job is to describe candidate elements so a human or an agent can tell them apart. With the labels stripped, two different menu items — New test and New tests from requirement — rendered byte-identically, making the error message useless and any automated choice between them a guess.

The change

removeNonInteractiveElements() gets an opt-in keepText option, false by default. When enabled, a non-interactive subtree is dropped only if it contains no visible text. simplifyHtmlElement() passes keepText: true, since it describes a single element and that element's own text is exactly what the caller needs.

removeNonInteractiveElements()'s existing behavior is unchanged: with keepText false the new condition short-circuits, and output on the full-page fixtures (test/data/github.html, test/data/testomat.html) is byte-identical to before. maxLength truncation still applies after simplification, as before.

Tests

New #simplifyHtmlElement block in test/unit/html_test.js covers the nested label, distinguishability of two similar labels, dropping of text-free nested markup, maxLength truncation, and that removeNonInteractiveElements() still strips the nested label by default.

npx mocha test/unit --recursive --timeout 10000 — 786 passing, 11 pending, 0 failing.