test: handle file URL paths with spaces

[TateLyman]

Summary

• Convert test harness file URL paths with fileURLToPath(...) so spawned node dist/index.js calls work when the checkout path contains spaces.
• Sync the legacy VERSION file to the current package.json version, 3.18.0.

Why

Running npm test from a checkout path such as New project 7 failed because URL.pathname produced New%20project%207, so Node tried to execute a non-existent encoded path. fileURLToPath preserves the real filesystem path.

Validation

• npm run build
• npm test before rebase: 391/391 passing
• Rebased onto current main / 3.18.0; npm test reached 392/393 passing, with one unrelated task-wait timeout
• Reran the timed-out test directly: node --test --test-reporter=spec --test-name-pattern "cli: franklin task wait reconciles stale queued tasks before blocking" test/local.mjs -> passing
• git diff --check