feat(patrol): add daily patrol digest aggregation

Per-cycle patrol digests were polluting JSONL with O(cycles/day) beads.
Apply the same pattern used for cost digests:

- Make per-cycle squash digests ephemeral (not exported to JSONL)
- Add 'gt patrol digest' command to aggregate into daily summary
- Add patrol-digest step to deacon patrol formula

Daily cadence reduces noise while preserving observability.

Closes: gt-nbmceh

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/cmd/molecule_lifecycle.go

@@ -215,13 +215,15 @@ squashed_at: %s
 		}())
 	}
 
-	// Create the digest bead
+	// Create the digest bead (ephemeral to avoid JSONL pollution)
+	// Per-cycle digests are aggregated daily by 'gt patrol digest'
 	digestIssue, err := b.Create(beads.CreateOptions{
 		Title:       digestTitle,
 		Description: digestDesc,
 		Type:        "task",
-		Priority:    4, // P4 - backlog priority for digests
+		Priority:    4,       // P4 - backlog priority for digests
 		Actor:       target,
+		Ephemeral:   true,    // Don't export to JSONL - daily aggregation handles permanent record
 	})
 	if err != nil {
 		return fmt.Errorf("creating digest: %w", err)