fix: surface resource-exhausted runner startup failures clearly

[forestileao]

Problem

Some runner failures hide the actual cause. Example: a full git clone on a tiny machine failed without surfacing a clear resource-exhausted or machine-too-small error. The workaround was using a shallow clone (--depth=1).

Expected

When a runner fails due to resource pressure or startup constraints, users should see a clear diagnostic instead of a generic failure.

Acceptance criteria

• Detect and surface common resource-exhausted runner failures.
• Preserve enough logs/error detail for debugging.
• Add coverage or a reproducible test case where practical.