controller: F7 atomic volume dumps + F6 no-single-copy + F5 stale-primary sweep (WIP, pre-build)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017CDMFpFx84pfviCTVuGGhf

controller/internal/backup/opstatus.go

@@ -11,7 +11,7 @@ import "time"
 
 // RestoreOpResult is the terminal record of the most recent restore op.
 type RestoreOpResult struct {
-	Op         string    `json:"op"`      // "restore" | "tier2-restore" | "offbox-restore"
+	Op         string    `json:"op"` // "restore" | "tier2-restore" | "offbox-restore"
 	Stack      string    `json:"stack"`
 	OK         bool      `json:"ok"`
 	Message    string    `json:"message"`