controller v0.264.0: the household is told when an update is undone or held, in its language

app_update_undone / app_update_held events (09 decision 15), on by
default and seeded once on existing boxes; R-606 update sentences as
key+args rendered per reader; R-646 startup applied-meta backfill for
apps current with the catalog; R-620 a disabled notifier WARNs once per
event type. Needs hub v0.120.0.

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

controller/internal/stacks/manager.go

@@ -154,6 +154,12 @@ type Stack struct {
 	UpdatePhase      string `json:"update_phase,omitempty"`
 	UpdatePhaseLabel string `json:"update_phase_label,omitempty"`
 	UpdateError      string `json:"update_error,omitempty"`
+	// UpdateErrorKey / UpdateErrorArgs (v0.264.0, R-606) are UpdateError as a bundle key + arguments,
+	// so a page renders it in the READER's language (UpdateErrorIn). UpdateError stays the Hungarian —
+	// what the API, the logs and older readers have always had. Empty key = an old or composed sentence,
+	// rendered as stored, never as an empty line.
+	UpdateErrorKey  string        `json:"-"`
+	UpdateErrorArgs []interface{} `json:"-"`
 	// updateHeld (R-480, v0.240.0) — the last update ended HELD, so UpdateError is the hold's own
 	// sentence („… leállítva marad"). It is shown only while that hold is in force; fillHoldReason.
 	updateHeld bool
@@ -243,6 +249,7 @@ type Manager struct {
 	undoCopier         volumeCopier
 	updateUndoHealthFn func(ctx context.Context, name string, timeout time.Duration, meta *Metadata) (bool, string)
 	probeRunFn         func(t probeTarget) *HealthProbeResult // the health wait's network probe; nil ⇒ runChecks
+	updateEventSink    func(UpdateEvent)                      // v0.264.0: the notifier; nil ⇒ no events
 	updateMemoryFn     func(newReqMB, newLimitMB, releasedReqMB, releasedLimitMB int) (refusal error, warning string)
 	updateDiskFreeFn   func() (freeGiB float64, ok bool)
 	updateNowFn        func() time.Time