[codex] Speed up native MySQL parser materialization

[adamziel]

What changed

This is stacked on #377.

• Creates PHP WP_MySQL_Token and WP_Parser_Node objects directly through Zend property writes instead of calling PHP bridge helper functions for every token/node.
• Builds parser node children as a packed array in one step instead of calling append_child() once per child.
• Keeps parsed query ASTs in native Rust form after next_query() and materializes the PHP AST lazily on get_query_ast(), caching that PHP object for repeated reads.
• Replaces hot parser grammar HashMap/HashSet lookups with dense rule entries and sorted lookahead vectors.
• Removes rule-name cloning and string comparisons from recursive parser matching.

Why

The first Rust extension PR kept the exact public PHP token and AST shape, but it still spent a large part of runtime crossing back into PHP for object construction and child appends. This PR keeps the public objects the same while moving that materialization work into the extension and reducing generic grammar lookup overhead.

Performance

Measured locally on PHP 8.2.29 CLI, Linux 6.12, AMD Ryzen 5 7430U, 2 visible cores, 7.2 GiB RAM. The Rust extension was built with cargo build --release. Each payload is a generated 50 MiB SQL file with unique statements and varied identifiers/literals: long multi-row inserts, CTE/window/subquery-heavy selects, and mixed DDL/DML. Timings exclude file_get_contents() and include tokenization, parser construction, next_query(), and get_query_ast() for every statement, so PHP-compatible AST materialization is included.

Payload	Size MiB	Statements	Tokens	PHP lex s	Rust lex s	Lex speedup	PHP parse s	Rust parse s	Parse speedup	PHP total s	Rust total s	Total speedup	Peak MB PHP/Rust	Failures PHP/Rust
long inserts	50.00	4,890	9,623,521	11.714	4.814	2.43x	107.580	23.059	4.67x	119.294	27.873	4.28x	1696.0 / 1672.0	0 / 0
edge selects	50.00	31,313	11,147,429	16.935	5.875	2.88x	130.798	22.880	5.72x	147.732	28.755	5.14x	1890.0 / 1854.0	0 / 0
mixed ddl dml	50.00	21,482	9,410,229	11.247	4.464	2.52x	100.169	17.859	5.61x	111.416	22.323	4.99x	1666.0 / 1644.0	0 / 0

Compared with the initial Rust implementation measured in #377, the native extension total time improved from 67.616s to 27.873s for long inserts, 87.148s to 28.755s for edge selects, and 88.876s to 22.323s for mixed DDL/DML.

Validation

• cargo fmt --check
• cargo build
• cargo build --release
• Extension-loaded focused parser/lexer suite: OK (183 tests, 1421183 assertions)
• Extension-loaded full mysql-on-sqlite PHPUnit suite: Tests: 667, Assertions: 1427673, Skipped: 2, Incomplete: 2