fix(php-transformer): preserve inherited border-box resets

[chubes4]

Summary

Preserves the common html{box-sizing:border-box} *,*::before,*::after{box-sizing:inherit} reset when projecting CSS into native WordPress blocks, and retains linked SVG-only logos as materialized image blocks.

Border-Box Root

• php-transformer/src/HtmlToBlocks/Style/AuthorStyleRuleProjector.php:authorStylesUseUniversalBorderBoxReset()
• The prior detector recognized only explicit *{box-sizing:border-box}, then injected box-sizing:content-box on generated Groups despite an inherited root reset.

Linked SVG-Only Logo Root

• HtmlCompilation::isLinkedSvgLogoAnchor() previously required the wrapper anchor itself to carry a logo/brand token. An unlabelled link around a descendant .logo containing only inline SVG returned null before its child could be converted, omitting the header artwork.
• LogoPattern also rejected SVG-only logo content because its text content was empty.
• The fix recognizes a descendant logo signal, materializes the safe SVG asset, and makes a percentage-width linked core/image resolve against its sized figure rather than its shrink-to-fit link wrapper.
• Existing upstream linked-SVG logo work was reviewed (#525); this closes the remaining wrapper-signal case rather than duplicating it.

Public Reproducer

• php-transformer/tests/unit/artifact-author-stylesheet-projection.php covers a root + universal inherited border-box reset with a width-and-padding Group.
• php-transformer/tests/unit/author-selector-semantics.php covers an unlabelled link wrapping a descendant .brand-logo with a width="100%" height="100%" inline SVG.

Verification

• php tests/contract/run.php
• php tests/unit/author-selector-semantics.php
• php tests/unit/artifact-author-stylesheet-projection.php
• php tests/unit/engine-support-css-specificity.php
• php -l src/HtmlToBlocks/HtmlCompilation.php
• php -l src/HtmlToBlocks/Patterns/LogoPattern.php
• php -l src/HtmlToBlocks/Support/SvgMaterializer.php
• Real supported static-site-importer import candidate browser proof at 1440x900 and 390x844: header SVG now materializes and loads 200 at 227.7x30; footer SVG asset also loads 200 at 227.7x30. Candidate document widths are exactly 1440 and 390, confirming no horizontal overflow after the inherited border-box fix. The footer is at x=-114 on mobile in both source and candidate, so that clipping is source-authored, not a transformation regression.

AI assistance: openai/gpt-5.6-terra via OpenCode was used to diagnose browser DOM/CSS behavior and implement the fix.