[PHP] Preserve site-builder post-content syntax during URL rewrites

[adamziel]

Rewrites mapped authorities inside the original bytes of builder post content, so JSON escapes, CSS escapes, HTML entities, shortcode syntax, and Base64 payloads stay intact. PHP serialization is parsed before its string leaves change, preserving its byte lengths.

The PR adds the 60-case site-builder corpus as the contract and makes every case pass. It also covers changed serialized lengths, changed Base64 payloads, encoded attributes, percent and CSS escapes, and nested JSON, serialization, Base64, HTML, and shortcodes.

Tests: ../vendor/bin/phpunit UrlRewriting (398 tests, 2,588 assertions; 7 skips); vendor/bin/phpstan analyse --memory-limit=1G.

[github-actions]

Pull pipeline performance — large-directory

Site: large-directory · 2,000+ plus targeted file-transfer scenarios files · 10,000 posts · 25,000 postmeta · PHP 8.5.9

Stage	PR	trunk	Δ	Status	Details
playground-sqlite-db-pull	8.03 s	8.06 s	⚪ -24 ms (-0.3%)	✓	condition=db-pull in PHP.wasm runtime=php.wasm 8.3 wp_mysql_parser=enabled mode=lexer native_lexer=verified native_token_stream=WP_MySQL_Native_Token_Stream native_token_count=18 native_parser=selected trunk: condition=db-pull in PHP.wasm runtime=php.wasm 8.3 wp_mysql_parser=enabled mode=lexer native_lexer=verified native_token_stream=WP_MySQL_Native_Token_Stream native_token_count=18 native_parser=selected
playground-sqlite-db-apply	3.51 s	3.57 s	⚪ -59 ms (-1.6%)	✓	condition=db-apply to SQLite in PHP.wasm runtime=php.wasm 8.3 wp_mysql_parser=enabled mode=parser native_lexer=verified native_token_stream=WP_MySQL_Native_Token_Stream native_token_count=18 native_parser=verified native_ast=WP_MySQL_Native_Parser_Node sqlite_driver_parser=verified trunk: condition=db-apply to SQLite in PHP.wasm runtime=php.wasm 8.3 wp_mysql_parser=enabled mode=parser native_lexer=verified native_token_stream=WP_MySQL_Native_Token_Stream native_token_count=18 native_parser=verified native_ast=WP_MySQL_Native_Parser_Node sqlite_driver_parser=verified
Total	11.55 s	11.63 s	⚪ -83 ms (-0.7%)

_{Numbers carry runner noise; treat single-run deltas as directional, not authoritative.}

_{📈 Trunk performance history — commit-by-commit timeline.}