fix(eval): decode file URLs before launching test wrappers

[sunrioa]

Summary

• convert Eval wrapper and shim file URLs with fileURLToPath() before passing them to child-process APIs
• preserve paths containing spaces, non-ASCII characters, and other URL-encoded characters
• keep the change limited to the six affected Eval test-harness launch points

The Eval harness previously passed URL.pathname directly to spawn() and execFile(). Because that value remains percent-encoded, a checkout path containing spaces was passed to Node with %20 instead of the native filesystem path, preventing the wrapper or shim from launching.

This change performs the platform-correct conversion at each affected child-process boundary. Production Runtime behavior is unchanged.

Fixes #4757

Verification

• npm run build
• npm run lint
• npm run format:check
• npm run typecheck
• npm run check:asf-headers
• npx knip --workspace apps/desktop
• npx knip --workspace packages/ui
• complete @maka/eval JavaScript and Python test suites
• complete @maka/runtime test suite
• npm run check:release — 194/194 passed
• reproduced the failure and verified the fix from a checkout path containing spaces

The repository-wide test command was also exercised. Unrelated Runtime Host process-exit/election timing tests remained intermittent; the same class of failure was reproduced on clean main, while isolated reruns passed.

AI use

Select exactly one:

• No generative tool made a substantive contribution
• Generative tooling made a substantive contribution

Tool(s) and scope: OpenAI Codex assisted with source inspection, implementation, and local verification. The resulting changes and this description were reviewed by me.

Checklist

• Tests cover the change and fail without it
• Lint, format, typecheck and the affected suites pass locally

Does this PR entail a change in behavior?

• Yes — limited to Eval test-harness file URL conversion; production Runtime behavior is unchanged
• No