Fix native renderer naming and add cross-platform output parity CI

[urbankrepel-povio]

Version 3.2.1 still generates different hook names in JavaScript and native because #94 landed on codex/rust-codegen-core, not main. This ports that fix and its parity workflow onto current main so the next release can include them.

Native follows JavaScript's operation-name collision handling, preserving controller-based hooks instead of falling back to path-based names. Enum names and metadata also match. The port preserves main's newer Zod compilation and enum null handling.

A separate CI workflow generates the checked-in Petstore schema using JavaScript and native on Linux and macOS, then requires identical file lists and exact SHA-256 hashes across all four runs. Files and manifests are retained as artifacts.

Validation:

• JavaScript and native full suites: 251 passed, 13 skipped in each mode.
• All 21 generated file hashes match locally; all 18 parity/regression tests pass.
• Native build, typecheck, lint, and independent integration review pass.