docs: publish matched XML and JSON serializer comparisons

[nth-bailey]

Adds a current, reproducible comparison page for native options, competitor serializers and PolyXML bindings. The tables separate XML from JSON, typed models from dynamic graphs, and serializer performance from generated-model overhead. Every figure comes from retained PolyXML 0.34.8 samples with source, generated models, locks, versions and hashes.

• Rust: generated owned/borrowed XML versus quick-xml Serde and serde-xml-rs; generated versus handwritten serde_json models; separate allocation diagnostics.
• Python: PolyXML versus xsdata on identical generated dataclasses, plus typed stdlib/lxml adapters and a separately labeled Pydantic XML reference. Timings exclude tracemalloc.
• Go/C#: refreshed native-model comparisons with full-field preflight checks. C# retains default-tiering order effects as diagnostics and publishes a separate six-process full-JIT control.
• Java: fresh two-fork JMH comparisons of direct codecs, Jackson and JAXB, with full-input checks, output lengths, heap allocation and the actual Woodstox provider recorded.
• C++/TypeScript: explicit matched-return-value coverage gaps. Historical results remain separate.

The page includes slower results as well as wins: specialized Python stdlib adapters win some cases, Go root methods add write allocations, and Jackson reads slightly faster than the Java direct codec on these projections.

Validation: Rust workspace format, strict Clippy and all workspace tests passed; 115 Python tests passed with 100% statement/branch coverage; Java interoperability tests passed; all 33 exported XML outputs passed independent checks; Python writer outputs also passed XSD validation; final version-guard smoke passed; strict docs build and benchmark-source Ruff passed. Builds and measured processes ran serially under memory caps. The standalone consumer's two existing generated single-match patterns require the style lint allowance recorded in audit.json; workspace Clippy passed without exceptions.