Handle prerelease Node.js versions without failing worker initialization

[Tsuyoshi Ushio (TsuyoshiUshio)]

Summary

• parse Node.js runtime versions with the existing semver dependency
• warn for valid prerelease versions instead of failing worker initialization
• preserve the parse error for invalid version strings

Fixes #842.

Why

The worker's version check split process.version on . and required exactly three components. A valid prerelease such as v26.8.0-alpha.0.0.0 therefore caused WorkerInitRequest to fail before the worker could start.

This behavior was exposed by the Azure Functions Docker hotfix PR:
https://dev.azure.com/msazure/One/_git/AAPT-Antares-Functions-Docker/pullrequest/16949790

The root problem is not in the worker: NodeSource package 26.8.0-1nodesource1 appeared to be a stable package version, but its installed Node binary reported v26.8.0-alpha.0.0.0. Production images expecting stable Node.js must still reject that artifact. This worker change is defense in depth so diagnostic version validation does not make the language worker unavailable for a syntactically valid prerelease version.

Tests

Red before the implementation:

Error: Could not parse Node.js version: 'v26.8.0-alpha.0.0.0'

Validated with fnm Node.js v22.22.3:

• npm run build
• npm run lint
• focused getNodeVersionLog tests: 4 passing
• full suite: 147 passing, 8 pending, 3 unrelated timing failures
• the 3 failed existing cases passed when rerun alone

[Tsuyoshi Ushio (TsuyoshiUshio)]

/azp run

[azure-pipelines]

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