R-699: a unit that holds no data is never an update-precondition copy (found live on 9202)

A just-installed app's unit, captured by the status refresh before any backup, satisfied
the precondition on its manifest time; tandoor's PostgreSQL was converted with no backup
of its database. Listed still; never a copy on Tier 1 or Tier 2. Red-proof RP6.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

controller/internal/backup/r659_whole_copy_test.go

@@ -41,7 +41,7 @@ func r659Manager(t *testing.T, files bool, tiers map[int]time.Time) *Manager {
 		if !ok {
 			return nil, false
 		}
-		return []RestorePoint{{Time: at.Format(time.RFC3339), Tier: 1}}, true
+		return []RestorePoint{{Time: at.Format(time.RFC3339), Tier: 1, DataProven: true}}, true
 	}
 	m.updateOffsiteTimesFn = func(context.Context) (map[string]time.Time, error) {
 		at, ok := tiers[UpdateTierOffsite]