feat: add services array to distinguish function and site runtimes

[HarshMN2345]

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[greptile-apps]

Greptile Summary

This PR adds a services array to the Runtime class to distinguish which service category (functions or sites) each runtime supports. The static and flutter runtimes are marked as sites-only while all others default to both.

• Adds SERVICE_FUNCTIONS/SERVICE_SITES constants, getServices()/setServices() with input validation, and includes services in the list() output.
• Marks static and flutter as site-only runtimes in Runtimes.php.
• New tests cover constructor/setter validation, list() output shape, and site-only runtime assertions.

Confidence Score: 5/5

Safe to merge; the change is additive and well-tested with no impact on existing runtime behavior.

The new services field is additive, the validation logic is straightforward, and the test suite covers the main paths including error cases. No existing behavior is altered — all runtimes that previously had no services argument now receive the same default of both services.

No files require special attention.

Important Files Changed

Filename	Overview
src/Runtimes/Runtime.php	Adds $services property, two constants, getServices()/setServices() with validation, and surfaces services in list() output. Validation guards for empty arrays and unknown values are present; duplicate entries are not deduplicated.
src/Runtimes/Runtimes.php	Marks static and flutter runtimes as SERVICE_SITES-only; all other runtimes keep the default [SERVICE_FUNCTIONS, SERVICE_SITES]. Change is straightforward and correct.
tests/Runtimes/RuntimesTest.php	Good coverage for the new feature: tests constructor throws on empty/invalid services, setServices validation, list() output shape, and site-only runtimes. One test hardcodes node-18.0 as the version key which could become a maintenance burden if that version is removed.

_{Reviews (5): Last reviewed commit: "fix: add PHPDoc type hint to satisfy PHP..." | Re-trigger Greptile}