Task: Make reporting's shell commands answer

Close V04's reporting-owned causes: three generated recipes pass none where a required uuid belongs, and the eight execution-step handlers return in silence when the workflow headers are absent, so the caller learns only that time passed.

• No generated recipe requires the caller to supply a server-owned identifier.
• A step handler that cannot attribute a message answers with an error instead of returning in silence.
• The replay records every generated command as answering, or as unable to run with its reason.

(Implementation strategy. Written when work starts; key decisions are distilled into the parent story's * Decisions at close, but the plan itself stays — it is the historical record of what we did.)

Manual QA scenarios (scaffolded via compass add test_scenario) that verify this task. Link new ones here as they're created; the scenario doc itself links back via its "Verifies task" field.