Move public API implementation files

[adamziel]

What it does

Moves the existing public API implementation files to *php* sidecar filenames with no line changes.

This is intentionally only a file-move PR. It does not add public loaders, native wrapper classes, or behavior changes; those stay in the stacked PR #271.

Rationale

This gives reviewers a clean baseline where GitHub shows the large implementation files as renames before #271 adds the native integration and loader changes.

Implementation

Moved these files at 100% similarity:

• components/HTML/class-wp-html-tag-processor.php -> components/HTML/class-wp-html-php-tag-processor.php
• components/HTML/class-wp-html-processor.php -> components/HTML/class-wp-html-php-processor.php
• components/XML/class-xmlprocessor.php -> components/XML/class-phpxmlprocessor.php
• components/DataLiberation/URL/class-urlintextprocessor.php -> components/DataLiberation/URL/class-phpurlintextprocessor.php

The class names are deliberately unchanged in this PR so the diff remains move-only.

Testing instructions

composer dump-autoload
php -l components/HTML/class-wp-html-php-tag-processor.php components/HTML/class-wp-html-php-processor.php components/XML/class-phpxmlprocessor.php components/DataLiberation/URL/class-phpurlintextprocessor.php
vendor/bin/phpunit components/XML/Tests/
vendor/bin/phpunit components/DataLiberation/Tests/URLInTextProcessorTest.php
vendor/bin/phpunit components/DataLiberation/Tests/MarkupProcessorConsumerTest.php components/DataLiberation/Tests/HTMLEntityReaderTest.php
vendor/bin/phpunit components/Markdown/Tests/MarkdownConsumerTest.php
git diff origin/trunk...HEAD --check