test(supervisor): cover runtime adoption states

[vernonstinebaker]

Summary

• add direct supervisor coverage for adoptInstance() so persisted runtime adoption is exercised without relying on higher-level boot reconciliation paths
• verify a live runtime with no health port is adopted as running
• verify a live runtime with an unhealthy HTTP port is adopted as starting while preserving its stored timing fields

Validation

• zig build test -Dembed-ui=false -Dbuild-ui=false --summary all