Phase 6: schedules, blocklists, allowlists (editors + effective state)

- Weekly schedule editor per device: a Monday-Sunday grid of blocking
  windows, including windows that cross midnight.
- Blocklist/allowlist editor per device: app (Android package / Windows
  process) and site (hostname) entries, tagged by the device platform.
- Effective desired state: a manual lock, an active schedule window, or
  neither. While blocked the allowlist is honoured (Spotify stays while
  other apps are blocked). Published retained with reason schedule/manual.
- Boundary-aware republish loop so a window turns on and off on time,
  and manual lock expiry is cleared promptly.
- CONTROL_TIMEZONE (default Australia/Sydney) with embedded tzdata, so
  wall-clock windows are evaluated in the family zone, not the container.
- Every change is written to the append-only audit log (FR-15).

Co-Authored-By: Paperclip <noreply@paperclip.ing>

internal/mqtt/payload.go

@@ -77,15 +77,19 @@ func deviceFromTopic(topic, suffix string) (string, bool) {
 // The shape is versioned with "v" and is consumed by the kids' clients in
 // Phases 4 and 5. Add fields; do not repurpose them.
 type Config struct {
-	V           int        `json:"v"`
-	DeviceID    int64      `json:"device_id"`
-	Name        string     `json:"name"`
-	Platform    string     `json:"platform"`
-	Locked      bool       `json:"locked"`
-	Until       *time.Time `json:"until"`
-	Allow       []string   `json:"allow"`
-	Block       []string   `json:"block"`
-	GeneratedAt time.Time  `json:"generated_at"`
+	V        int        `json:"v"`
+	DeviceID int64      `json:"device_id"`
+	Name     string     `json:"name"`
+	Platform string     `json:"platform"`
+	Locked   bool       `json:"locked"`
+	Until    *time.Time `json:"until"`
+	Allow    []string   `json:"allow"`
+	Block    []string   `json:"block"`
+	// Reason is why the device is locked: "schedule" for an active weekly
+	// window, "manual" for a lock from the dashboard. It is omitted when the
+	// device is not locked. It is additive (Phase 6), so v stays 1.
+	Reason      string    `json:"reason,omitempty"`
+	GeneratedAt time.Time `json:"generated_at"`
 }
 
 // ConfigVersion is the current schema version of Config.