v0.109.0: soft-quota gate + usage bar + offsite report status (SLICE 4)

QuotaGB rides the descriptor into OffboxTarget; RepoSizeBytes persisted
from restic stats. Pre-run gate: >=100% refuses NEW backups (Hungarian
notice + operator alert) but prune STILL runs (red-proofed) and restore is
never gated; >=80% warns. /backups usage bar (quota>0 only). The hub
report gains the non-secret offsite status object for the OffsiteChecker.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PSK5g6qYLknKj8u3QAFEr6

controller/internal/report/builder.go

@@ -170,6 +170,9 @@ func BuildReport(
 		if host, user, port, repoPath, ok := backupMgr.OffboxCoord(); ok {
 			r.DRRecipe.OffsiteRestic = &DRResticCoord{Host: host, User: user, Port: port, RepoPath: repoPath}
 		}
+		// SLICE 4: the non-secret offsite status object — the hub's OffsiteChecker input (fill +
+		// staleness). nil (absent on the wire) when no offbox target is enabled.
+		r.Offsite = backupMgr.OffboxReportStatus()
 	}
 
 	if debug && logger != nil {