fix: emit dedicated runtime imports in generated clients

[urbankrepel-povio]

Generated Axios clients imported RestClient from the package root, pulling unrelated runtime exports into consumer builds. Both TypeScript and native generators now emit /axios for Axios clients and retain /native for native clients. Query imports use /query, including legacy root-path configuration.

Shared REST utilities accept native Headers and unknown errors without Axios types. Documentation lists runtime subpaths, and regression tests inspect emitted imports across both generators. Existing root exports remain available for compatibility.

Validation:

• TypeScript 7.0.2 typecheck, lint, and package/native builds passed.
• TypeScript and native test runs each passed 799 tests (13 skipped).
• Rust default-import regression passed.
• Package scripts and references checked after removing the dedicated optional-Axios verification script and CI step.

Local validation is separate from GitHub CI results.