fix(php-transformer): keep visually hidden class rules on preserved markup

[chubes4]

Problem

Visually hidden screen-reader text paints after import. A product card shows the label and the amount together where the source shows only the amount. The label stays in the DOM, but the clip/1px rule that hid it does not apply.

Root cause

Author stylesheet projection rewrites a class rule onto a semantic marker or an inline-layout carrier and drops the authored selector. That is correct when conversion emits the marker or carrier. Preserved markup (a repeated collection, extracted chrome) keeps the class and does not emit the marker, so the hiding declarations never match. The label renders as normal text.

Fix

When a rule's declarations are the visually-hidden clip pattern (absolute 1px box, overflow hidden, clip or clip-path), keep the authored class selector alongside the projected form. The class still hides the text wherever the markup lands. Tag-only selectors are not carried.

Regression test

php tests/unit/visually-hidden-authored-clip.php

Unfixed (git stash of the projector):

FAIL: a clip/1px class inside a preserved link stays visually hidden
FAIL: a carrier-projected clip class still hides the preserved label
FAIL: a clip-path inset pattern is the same visually-hidden class rule
visually hidden authored clip FAILED: 5 passed, 3 failed

Fixed:

visually hidden authored clip passed: 8 assertions

Also passed: visually-hidden-menu-toggle-label.php, dead-projected-selectors.php, css-value-inspector.php, author-selector-semantics.php, artifact-author-stylesheet-projection.php.

Verification

Fresh import of the captured shop route with this commit vendored into Static Site Importer (blocks-engine b3c4a143f). Playwright at 1440px, label whose text is Price, next to the visible amount:

	box (w×h)	position	clip	visible
loop-2 baseline	32.8×22.5	static	auto	yes
this import	1×1	absolute	rect(0px, 0px, 0px, 0px)	no
source capture	1×1	absolute	rect(0px, 0px, 0px, 0px)	no

The amount stayed visible at 42.9×22.5 on both imports. The label text remained in the DOM. Verification site was stopped and deleted.

Fixes #2239

AI disclosure: implemented by xAI Grok 4.7 via OpenCode (opencode run), orchestrated and reviewed by Claude (Anthropic).