Preserve inline SVG phrasing geometry

[chubes4]

Summary

• materialize passive inline SVGs as native RichText image objects when they participate in phrasing flow
• preserve linked SVG semantics and source dimensions without introducing core/html fallback
• recognize generated SVG assets under source-relative paths such as website/assets/materialized-svg/
• retain standalone core/image output for media layout boundaries

Fixes the remaining inline SVG portion of #624.

How to test

1. Check out this branch from a fresh clone.
2. Run cd php-transformer && composer test.
3. Confirm all canonical contracts, unit tests, 244 parity fixtures, and package install proof pass.
4. Inspect the artifact-level contract in php-transformer/tests/contract/run.php and confirm a source-relative SVG next to a heading serializes as a native paragraph image object rather than core/html.

Compatibility

• No extension paths or public APIs change.
• Existing unsupported or unsafe SVGs retain their bounded fallback behavior.
• The behavioral change is limited to passive generated SVG assets that WordPress RichText can represent natively.

Supplementary evidence

A composed Static Site Importer browser run retained 291/291 editor-valid native blocks, removed the broken_svg finding, and eliminated the prior -8px cumulative page offset. The exact visual gate remains tracked separately by Automattic/static-site-importer#489.

AI assistance

• AI assistance: Yes
• Tool(s): OpenAI GPT-5.6 Sol via OpenCode
• Used for: Root-cause analysis, implementation, regression coverage, and verification in collaboration with Chris Huber.