Release Core v0.2.79 with typed pre-execution runtime failures

[AntoineToussaint]

Publish the merged generic runtime contract from #186 so Codefly agents can consume typed pre-execution test failures.

Release contents:

• RuntimeWrapper error responses are ERROR / ERRORED with zero counts.
• environment classification includes pre-execution runner diagnostics.
• Go module setup preserves actual diagnostics for malformed project environments.

Required verification: tag immutable v0.2.79, then update the real Go agent and prove its malformed-go.mod path returns typed ERRORED/env-blocked rather than UNKNOWN.