v0.262.0: six defects two drill nights found in the update, remove and hold paths

R-630 (P1): waitUpdateHealthy kept the probe inside `if hc != nil && len(hc.Checks) > 0`, and when
findProbeContainer returned "" its else set last="no probe container" and LOOPED - the settle path
sat in the outer else, unreachable. So verifying could only time out and failAndHold then stopped a
working app. Measured on paperless-ngx: three containers healthy, failed at +313.0s, front door 404
after. It now falls through to the same settle path with a WARN naming the candidates.

The probe target is decidable now: HealthCheckConfig.Container plus findProbeContainerMeta resolve
by exact stack name -> explicit container -> a UNIQUE prefix -> nothing with the candidates
returned. The old rule took the FIRST prefix match. A skipped stack records why instead of silence.

R-634 (half): RemoveStack refused on the !Deployed FLAG while the machine had containers, a compose
file and an app.yaml. It now asks whether anything EXISTS. The mechanism producing the bad record is
still not diagnosed and R-634 stays open for it.

R-633/R-626: RemoveStack consults UpdateGuards.Busy and IsUpdating and refuses with the app's own
sentence - the product already refused this clash for update and for restore. And because `down`
returning 0 is a request not a result, the project is watched for 25s afterwards, anything carrying
its label is removed by name with its labels logged, and the answer carries `verified`.

R-621: failAndHold writes compose logs --tail 400 into <stackdir>/hold-logs/<ts>/ BEFORE the down
that destroys them. Two existing tests pin the compose sequence and correctly caught the new step;
their expectations are updated with the reason that the ORDER is the assertion.

R-614: RemoveStack calls ClearUpdateState.

NOT in this release: R-625 (a held app still renders an Update button). Named, not half-done.

Three new sentences, each born as a key in both bundles. Four red-proofs seen failing.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

controller/internal/stacks/manager.go

@@ -127,6 +127,11 @@ type HealthCheckDetail struct {
 	Status  int    `json:"status,omitempty"` // HTTP status code (for http/api)
 	Latency string `json:"latency"`          // e.g. "45ms"
 	Error   string `json:"error,omitempty"`  // error message if unhealthy
+	// MessageKey is the i18n bundle key for Error when the text is a PRODUCT sentence rather than a
+	// transport error. It follows util.MsgError's contract: Error carries the Hungarian bytes (the
+	// default language), MessageKey lets a localising consumer render the other one. Added for
+	// R-630, whose "no health check ran" detail is the first such sentence here.
+	MessageKey string `json:"message_key,omitempty"`
 }
 
 // Stack represents a docker compose stack on disk.