feat: add Node 26 runtime

[HarshMN2345]

Summary

• Register Node 26 (node:26.5.0-alpine3.24 → openruntimes/node:v5-26), published in open-runtimes 0.13.17

Test plan

• Run PHPStan / existing test suite

[greptile-apps]

Greptile Summary

Registers Node.js 26 as a supported runtime.

• Adds node:26.5.0-alpine3.24 as the base image.
• Maps Node 26 to openruntimes/node:<version>-26.
• Declares x86 and ARM64 support.

Confidence Score: 5/5

The PR appears safe to merge with no actionable defects identified.

The new runtime entry follows existing Node registration conventions, and repository consumers and tests dynamically accommodate the additional version.

Important Files Changed

Filename	Overview
src/Runtimes/Runtimes.php	Adds a Node 26 runtime entry consistent with the identifiers, image-tag structure, architecture support, and ordering of recent Node registrations.

_{Reviews (1): Last reviewed commit: "feat: add Node 26 runtime" | Re-trigger Greptile}