Improve generic SSI matrix pattern recognition

[chubes4]

Summary

• improve generic HTML-to-block recognition for r10 SSI matrix gaps across forms, media, navigation, and repeated footer menus
• preserve runtime-target controls when scripts need native DOM nodes while converting non-runtime controls to readable blocks
• add parity/contract coverage for linked media, background images, runtime inputs, and repeated navigation

Testing

• php php-transformer/tests/parity/run.php
• php php-transformer/tests/contract/run.php

AI assistance

• AI assistance: Yes
• Tool(s): openai/gpt-5.5 via OpenCode general subagents
• Used for: r10 matrix diagnostic analysis, transformer patch drafting, and test fixture updates