Clean up native parser follow-ups

[adamziel]

What it does

Cleans up the native parser follow-up from #381 so the merged code reads as permanent code, not review scaffolding.

It replaces duplicated inline verifier logic with one tests/tools/verify-native-parser-extension.php entry point for mysql-on-sqlite. The parser-extension workflow and PHPUnit bootstrap both call the same verifier:

php -d extension=../php-ext-wp-mysql-parser/target/debug/libwp_mysql_parser.so \
  tests/tools/verify-native-parser-extension.php

It also collapses WP_PDO_MySQL_On_SQLite::create_parser() to one token selection and one parser reset/create return, and rewrites native parser test comments to describe behavior instead of PR review history.

Rationale

#381 landed functional native parser support, but a few follow-up surfaces still carried review-era wording and copied verifier blocks. That makes future changes harder to read and easier to drift: native parser routing, Rust AST handle storage, wrapper identity, and materialized child behavior were being checked in multiple places.

The verifier now pins that runtime contract from one script: extension loaded, WP_MySQL_Lexer resolves native, WP_MySQL_Parser delegates to WP_MySQL_Native_Parser, the SQLite driver returns a native-backed AST, native wrapper handle properties are absent, child identity is stable, and materialized child mutations survive.

Implementation

Added wp_sqlite_verify_native_parser_extension() with a shared delegate check:

function wp_sqlite_assert_native_parser_delegate( WP_MySQL_Parser $parser, string $context ): void {
    $reflection = new ReflectionObject( $parser );
    if ( ! $reflection->hasProperty( 'native' ) ) {
        wp_sqlite_native_parser_verification_fail( $context );
    }

    $native_property = $reflection->getProperty( 'native' );
    $native_property->setAccessible( true );
    if ( ! ( $native_property->getValue( $parser ) instanceof WP_MySQL_Native_Parser ) ) {
        wp_sqlite_native_parser_verification_fail( $context );
    }
}

WP_SQLITE_REQUIRE_NATIVE_PARSER_EXTENSION=1 in the PHPUnit bootstrap now loads that verifier instead of inlining the same checks.

create_parser() now selects tokens once:

$tokens = $lexer instanceof WP_MySQL_Native_Lexer
    ? $lexer->native_token_stream()
    : $lexer->remaining_tokens();

return $this->reset_or_create_parser( $tokens );

The WordPress PHPUnit extension setup keeps its container-specific verifier, but factors the repeated reflection checks into the same small helper shape.

Testing instructions

cargo fmt --check
bash -n .github/workflows/wp-tests-phpunit-native-extension-setup.sh
node --check .github/workflows/wp-tests-phpunit-run.js
php -l packages/mysql-on-sqlite/tests/tools/verify-native-parser-extension.php
php -l packages/mysql-on-sqlite/tests/bootstrap.php
php ./vendor/bin/phpcs .github/workflows/wp-tests-phpunit-native-extension-setup.sh packages/mysql-on-sqlite/tests/bootstrap.php packages/mysql-on-sqlite/tests/tools/verify-native-parser-extension.php packages/mysql-on-sqlite/src/sqlite/class-wp-pdo-mysql-on-sqlite.php packages/mysql-on-sqlite/tests/mysql/native/WP_MySQL_Native_Parser_Node_Identity_Tests.php packages/mysql-on-sqlite/tests/mysql/native/WP_MySQL_Parser_Instanceof_Tests.php

cd packages/mysql-on-sqlite
php -d extension=../php-ext-wp-mysql-parser/target/debug/libwp_mysql_parser.so tests/tools/verify-native-parser-extension.php
php ./vendor/bin/phpunit -c ./phpunit.xml.dist tests/mysql/native/WP_MySQL_Parser_Instanceof_Tests.php tests/mysql/native/WP_MySQL_Native_Parser_Node_Identity_Tests.php tests/mysql/native/WP_MySQL_Native_Parser_Node_Cycle_Tests.php
WP_SQLITE_REQUIRE_NATIVE_PARSER_EXTENSION=1 php -d extension=../php-ext-wp-mysql-parser/target/debug/libwp_mysql_parser.so ./vendor/bin/phpunit -c ./phpunit.xml.dist --filter 'WP_MySQL_(Native_Parser_Node_(Identity|Cycle)|Parser_Instanceof)_Tests'
php ./vendor/bin/phpunit -c ./phpunit.xml.dist tests/WP_SQLite_Driver_Query_Tests.php
WP_SQLITE_REQUIRE_NATIVE_PARSER_EXTENSION=1 php -d extension=../php-ext-wp-mysql-parser/target/debug/libwp_mysql_parser.so ./vendor/bin/phpunit -c ./phpunit.xml.dist tests/WP_SQLite_Driver_Query_Tests.php

CI is passing on 3f4153f, including the PHP 8.0-8.5 Rust-extension matrix and WordPress PHPUnit Tests / Rust extension.