Expose status projection reasons

[yvette-carlisle]

Summary

• add status_projection_reason to operator run status JSON/text when visible running status is promoted from a different attempt status
• explain whether process, thread, protocol, or app-server metadata caused the projection
• cover terminal/live-thread and terminal/live-process projection paths in status tests

Validation

• cargo make fmt-check
• cargo make check-rust
• cargo make test
• cargo test -p decodex operator_status_
• git diff --check origin/main..HEAD